Bf and Ps1 are way too fun. Using QD to hop around on the platforms and perform all kids of shananigans and tricks to fool and confuse your opponent never gets old. Imo Both are great, but I think BF is just a tad better, because it's stationary all the time, unlike PS1 where a stage transformation can sometimes throw you off and put you in a bad position (Or it can work in the reverse giving out oppurtunities to do some Wall infinites, but a good player will most likely avoid it).
Also, YI is like, my rarest stage. I usually end up playing on Ps1 and SV like 80% of the time lol.