Uh, Street Fighter is obvi way bigger than the Tekken community. SRK has 104,763 people registered on it. THere is also a SF4 TV show in korea.
On the is Smash legit question, of course it is a legit fighting game. But why would you want to put the effort into something as unbalanced as smash? Character specific infinities in match ups that are stupid easy to do? Stage banning to try and get the game back to balanced? random variables of, oh maybe thats death maybe its still live able? Not being able to play characters because they don't have KO viability (Lookin at you Sonic)? And a development team that could care not care less about the compettive side?
Or you could play street fighter...where they host in house tournaments, and sponsor tournaments for there games. Run by Capcom, who responds to the fan base and directly interacts with them, the tourny ones not the casuals. Or you could get your voice drowned out by kids who want Tails in the game, rather than you know...balance changes.