i was planning on catching up on all the bands' music before answering this buuut that's probably not going to happen so apologies to everyone for having incredibly boomer answers lol
popipa: everything but happy happy party (jk... honestly atp hhp has become endearing to me in its own way). umm but circling has been my eternal answer but there are so many others i love so much in so many different ways... returns, light delight, mae ni susume, 337, hello wink, setsunai sandglass, hashikimi, initial, BOF, hoshi no yakusoku... i enjoyed seishun TBC a lot as a whole but five letters is my fave i think... basically they are all good :)
afterglow: YOLO, sensenfukoku, and my favorite debut song (well til mayoiuta now)/the reason taki fell in love w them (in my hc): that is how i roll
pasupare: mou ichido luminous and wakuwaku meets trip. but also: shuwa
roselia: R, neo-aspect, avant-garde history, determination symphony, whatever song i most recently heard live gdfhgdh
harohapi: wacha mocha pettan koushinkyoku... sorry this answer is so underwhelming and boring fhgdhghd
morfonica: i rly need to listen to their discography more to get a clearer idea of this bc i enjoy a lot of their stuff but chikai no wingbeat goes so crazy live that's what i will go with in this moment
RAS: beautiful birthday, unstoppable, maybe declaration? i have been a little bored w/disinterested in RAS recently unfortunately but all their songs are perfect live so. also shouts out to gekidou cover
mygo: is all of them an acceptable answer (but umm. genuinely i struggle w this bc i adore all their songs, i default to tanebi but i don't think i have any actual conviction in loving that more than the others gfhdfhhd, i also particularly love otoichie, silhouette dance, mayoiuta, and kokyuu... and utakotoba... and all of them... (also again i am obligated to shout out moudoku ga osou ESP the live version where it follows straight from henceforth bc that makes me vibrate at the speed of sound))
ave mujica: prooobably kamisama baka or black birthday?? but i'm not sure, again they are all good live which is a huge factor in my love of a song... i'm excited to see/hear what's to come from them
vtubers: uhh their song is cute ig