RBS vs. RB2 is an eternal battle that tortures any real fighting enthusiast. Which game to play? Which one should I sink the time into? Don't even try to play both, you'll have inputs and chains confused and eat dirt quickly. I feel like I like the core gameplay of RB2 more, but the music, character selection, character interaction and cutscenes of RBS more.
Real Bout Dominated Mind for the PSX is a nice middle ground, but it's still missing Xiangfei and Rick...
I have no idea why they couldn't have made a Real Bout with Xiangfei, Rick, Alfred, Nightmare Geese, White, the EX characters from Special and all the normally playable characters in RB2's engine, or even a sequel with a slightly upgraded engine.