So far that I have tried and have to keep as a staple are RE, ICS, FM, WSP, CW. Runners up are JS, FB and candle source. CS is a good one too but not sure they have enough I absolutely have to have to justify shipping. Would love to try Bittercreek, Elements, Flaming and more from NG. Peak (now Keystone) I am unsure about since they seem to always lack stock and Brambleberry is high shipping and slow TAT for me.
Edit to add the reason why: for every reason I love fragrance oils which is either they work well for my methods or just smell so amazing that I cannot live without it.