I agree that I have the most fun in phantom but if you want to learn to master side shifts and brs I think venom and flash (maybe under some tutelage from texasalex or slow-train) are the best places to learn. This because you have to be so very exact in venom and flash, especially when competing with the likes of those guys mentioned above. Try to find them on youtube and have a look at what they're doing and you'll understand what I mean (if not agree )

Honestly I think Flash and Venom gets too much flack from phantom pilots.