The Moon

dark is their best album tbh but you might want to delve into:

GALLOWS/AVANTGARDE are DARK's marginally less attractive siblings, similar song flavor so you can't go wrong with them.

if you want to look at their older stuff, then i'd say these three:
greedy dead souls: their older style with more mood and songs that are slow but not quite ballads, highlights being latinmeria, mujun to sora, rasen, rew. but hazuki's "old" voice might take getting used to.
the avoided sun: similar to gds, worth checking out for forgiven and prominence
I BELIEVE IN ME: people are really split on this album but THIS COMA and BEFORE YOU KNOW IT are kind of the bridges between their old ballads/slower songs and new

skip SHADOWS & INFERIORITY COMPLEX imo

& i'll throw SORROW from SINNERS-EP a bone here too because it's a nice ballad and their nicest pv

idk how popular of an opinion this is but i think Inferiority Complex is by far their best, which is real weird for me to say cuz i'm not really into metalcore and this album is very much lots of that
but the energy is 10/10 on that record and the drums have so much life in them. they're mastered real loose and imho makes the drums every album after sound overprocessed / clicky. also i feel like this is the album where hazuki really dialed in how he wanted the double tracking his vocals to sound.
I Believe in Me feels like the rough draft of this album & Exodus like its B-sides.
i guess it's a real typical genre and nothing terribly innovative but if you want to hear the guys give a great performance on an album where they knew exactly what they were going for it definitely delivers.
but if you hear the first track & don't like it i don't think any of the rest would be different enough to change your mind.

the avoided sun is their only album having actual variety, but you'll be probably severely disappointed by every other album of their afterwards x