wild world/city folk, they're the most nostalgic for me and the main theme is probably my favourite song in the entire series. the gamecube track is objectively the catchiest though haha
I like the gamecube tracks and NL tracks for different reasons. WW/CF imo didn't have a great soundtrack but I remember it well due to it being the one I spent the most time with. I'm not really sure which soundtrack to pick out of the former two though - a mix of those styles would be lovely!