Rank Meanings

S: YES. These are my go-to games.
A+: Very Fun! These have good story and/or mechanics that really stuck with me.
A: Some of my favorite games that I'll often return to for a quick session.
B+: These games definitely scratch the itch.
B: When I'm itching for something different, I'll reach for these games. They're still very fun in their own right- just not my main games.
C+: These games stand out amongst the rest below them. Perhaps it's an interesting gimmick that could be taken further, or needs some fixes before ascending to a higher tier.
C: The Catch-all tier. Games here don't really click for me, but I don't necessarily have anything against them. They're alright, or I just played them for credit.
D: I've got my qualms with these games...
E: I'm not a fan of these.
DJ Max Disrespect: absolute blight on the genre, like why do you exist

Game List

S Tier

Rotaeno
Rhythm Doctor
WACCA
Groove Coaster
vivid/stasis

A+ Tier

DJMax Respect
Unbeatable
Chunithm
Deemo I
Muse Dash

A Tier

Cytus 2
Taiko
Arcaea
Sound Voltex
Paradigm: Reboot
Phigros
Theatrhythm Final Fantasy
Music Diver

B+ Tier

Lanota
Thumper
Noisz STARLIVHT
Pump It Up
NotITG
Rizline

B Tier

Tone Sphere
Cytus 1
VOEZ
RAVON
Orzmic
EZ2ON Reboot:R
Etterna
Spin Rhythm XD
Just Dance
Tapsonic Bold
Lyrica
RYCEAM
Dynamix
Rhythm Thief: The Emperor's Treasure
Quaver

C+ Tier

Shinobi Slash (シノビスラッシュ)
Hexa Hysteria
Old School Musical
ADOFAI
Polytone
Sparkline
D4DJ Groovy Mix
Takumi³
Sequence Storm
Milthm

C Tier

Deemo II
Dance Rail 3
Overrapid
Osu!
COXETA
ChainBeeT
Anxiens
World Dai Star
MUSYNX
Chrono Circle
Friday Night Funkin Mods

D Tier

Deemo Reborn
Avicii Invector
Malody
Cytoid
Friday Night Funkin
RoBeats
Kalpa
Project Sekai (JP)

E Tier

Project Sekai (EN)
Fortnite Festival

DJMax Disrespect Tier

Beatstar

Music Games

Geometry Dash [B]
Project Arrythmia [B+]
soundodger+ [B]
Just Shapes and Beats [B+]
Piano Tiles 2 [E]
Bit.Trip Beat [B]
Bit.Trip Core [D]
Bit.Trip Void [C+]
Bit.Trip Runner [B+]
Bit.Trip Rerunner [A]
Bit.Trip Runner 2: Future Legend of Rhythm Alien [S]
Bit.Trip Runner3 [D]
Bit.Trip Fate [B+]
Bit.Trip Flux [A+]

Not Played Yet

Maimai DX
O.N.G.E.K.I.
Sixtar Gate
Melatonin

Not Experienced Enough to Rank

Beatmania IIDX
Project Diva
Dance Dance Revolution
EX-XDRiVER
Crypt of the Necrodancer
Liminality
Volthopper

Dead (as in unplayable/EOS + no offline)

Seven's Code

Justifications

C Tier

A Dance of Fire and Ice

I know for a fact some people are going to get angry at my placement of ADOFAI, so I will paste my steam review verbatim to explain why:

"Good music, cool ideas, too unforgiving.

This game isn't for people who just want to play through a rhythm game, it's for those who seek mastery regardless of the pain required to get to that point.

You can't miss at all, and practice mode doesn't allow you to play through the entire song, only up until just after your best score. The game is less focused on getting you used to particular charts, but instead on particular sections one at a time. This doesn't work for me, and only feeds into frustration. (Apparently practice mode allows for practicing the whole song on custom charts only, which makes absolutely NO sense)

Neo Cosmos was fun though due to lax checkpoints, except for that one section in T4-X, you know the one :("

I do respect the game, however (especially Neo Cosmos), hence the C tier placement.

Osu!

I only play Mania and (sometimes) Standard. I would have added the mode-specific icons, but it was a oversight on my part.

D Tier

Deemo Reborn

The gameplay is good, but the song list lacks several signature songs due to copyright/creative/scandal issues. It also butchered the story of the original game, in my opinion.

Avicii Invector

Interesting concept, but excessively hard to read. Several of the harder charts suffer from unreadability due to the note density. The note speed also depends on your current combo. Missing a note instantly compresses your POV.

Cytoid

Community based rhythm game lends itself to overly hard charts, which is alright! ...but the judgement timing window is REALLY strict.

FNF (base)

Still waiting on the full game to come out. I don't exactly trust the developers to finish it anytime soon. UNBEATABLE has made far more progress during FNF's radio silence, and that unsettles me.

Robeats

Rotating song shop, P2W scoring mode with purchasable gears... immensely dense charting on higher difficulties doesn't bode well with roblox's constant frame drops...

Kalpa

Irritating free song unlock system that makes Arcaea's look bearable in comparison, cosmetics are now locked to a gacha system, The charting style is absolutely exhausting to play

JPSekai

Why would you ever play the English version? It still has the issues of the English version listed below, but input drops are MUCH less prevalent.

E Tier

PJSK (EN)

Project Sekai has no Technical Score, unlike D4DJ, World Dai Star, or Anxiens. Grinding to upgrade characters is also insufferable, even when compared to D4. Instead of just getting 8 4* characters to level 80, you also have to do a bunch of extra bullshit on top of that which can take multiple events to grind for. There are also plenty of cases of note drops :(

Also JP players are a lot more favored in general. They have bug fixes AND QOL features first, when they should be applied to every version at once. (For example, fast/slow display!!) Also, OLD BUGS somehow reappear when the English version catches up to where the bugs were originally in the JP version. wtf why

Fortnite Festival

Down here for many of the same reasons as Beatstar, but compensates for bad monetization in decent gameplay.

The Good

Game is playable, no note drops as far as I can tell.

The Bad:

$5/song cost
Undercharted songs
Some songs just shouldn't have certain instrument charts because they're repetitive.
$20 battle pass for ONLY FOUR SONGS. Sure, the price lines up with the other song prices, but that doesn't make it any better.
Large file size. Fortnite should just be a smaller package where you download assets based on the subgames you're interested in. Having to reinstall 70+gb of data because EGS can't recognize my external drive every Tuesday is not fun.

DJMax Disrespect Tier

Beatstar

This is a doozy of a game. To prevent myself from going on a tangent, I'll just list every grievance I have.

Gameplay:

You are not allowed to miss ANY notes. It's an antiquated mechanic borrowed from piano tiles that only exists as an annoying way to make money.
Constant input drops. They're more plentiful the longer the app is open. They haven't been fixed in the 2.5+ years of the game being released, and probably never will.
The calibration tool is not easy to use, and only let you use 10ms increments. Your offset also tends to change in-between game updates, for some reason.
Perfect+ timing windows get smaller as the game speeds up, when they shouldn't. Note speed also increases the frequency of input drops.

Monetization:

The Clash Royale-style chest system doubles as a stamina system. Fill your three card case slots and you can no longer play the game. It takes 7 full plays of songs before you run out of space. (It used to be 9 plays, but it was changed for some reason. likely money...)
Note that the paid unlimited play is 25 gems per 30 minutes or $5 per week. yuck.
The battle pass contains 9 exclusive songs, one of which is free. These songs do get added into normal progression later on. However, the battle pass does not give you Unlimited Play, meaning you're still bound by the 7 play stamina system regardless of your support to the game. Ridiculous.
Some tour passes lock specific songs behind the premium pass. >:(
A special box does exist that allows you to specifically buy previous season songs, but it's still subject to a random pull, AND you have to wait 2 seasons for it to be put into the box.
The Deluxe Update added additional (usually harder) charts to existing songs. However, you only get Deluxe cards at 1/2 the rate of normal, and the Deluxe box requires 100 cards to unlock at its upper limit. This essentially means you have to grind 4x as much for a Deluxe chart versus a normal one.
The only way to get free unlimited play is to unlock every song available in the normal game progression. (This excludes events and shop-only songs.) Before the Deluxe update came out in late 2022, this was a grindy, yet plausible goal. Nowadays, it's virtually impossible due to the unlock speed of Deluxe charts.
Otherwise, you have to pay 25 gems per 30 minutes, buy a box from the shop for 20 minutes, use one of the few promo links for 30 minutes each, or pay $5 for 7 day's worth.
Song prices are the highest they've ever been. You can expect to pay up to at least double the normal price compared to other rhythm games. (Most games rarely go above $1.25-$1.50 per song...)
Buying song boxes from the shop do not allow you to choose a song directly. It's still a random draw.
Events occasionally have exclusive songs, locked behind a gacha wheel. There are multiple prize tiers, with these songs in the grand prize tier. This tier has a 10% chance of dropping, with a 10-spin pity. Most events only have 1 or 2 songs up for grabs, and there can be up to 9 total prizes in the grand prize tier. This means your chances of getting one of these songs can be as low as 1.1%. Since each spin costs 10 tokens, you'll need to spend a maximum of 900 tokens to get your target prize. It's impossible to get that many by playing the events normally, so you may be resigned to coughing up some cash.

With all of these problems, I cannot recommend this game to anybody in good faith. If you want to play a game in this style, try TapTap Reloaded, which happens to have some of Beatstar's song list. (it also has very little, if any monetization.) If even this scathing review doesn't deter you, then please play the modded version of the game to save your sanity. It unlocks all the songs for you and has (some) quality of life features that the developers of the original will likely take another 2 years to implement. (early/late, customizable judgement colors, access to previously inaccessible songs, penalty-free misses) In addition, the community has made some really cool custom charts that are playable using the mod.