My particular preferences for Love Live!-related sources are as follows:

"START:DASH!!" by μ's

"Binetsu kara Mystery" and "A-NO-NE-GA-N-BA-RE!" by lily white

"Koi no signal Rin rin rin!" and "Kururin MIRACLE!" by Rin Hoshizora

"Shocking Party" and "Private Wars" by A-RISE (If you need some resources for "Shocking Party", ask MtH)

"SILENT PAIN" and "JIMO-AI Dash!" by Aqours

"GALAXY HidE and SeeK" by AZALEA

"Motto ne!" by Kanan Matsuura

Anything related to Nijigasaki (ESPECIALLY Rina Tennoji and Mia Taylor)

"Tiny Stars" by Kanon Shibuya and Keke Tang

"On your mark" by the Hasunosora Girls' High School Idol Club

"Do! Do! Do!" by Mira-Cra Park!

Background music from the anime adaptations

The original soundtracks of the games

Of course, I don't mind if you use other Love Live!-related sources (aside from "Snow halation"), but these would make me especially happy!