Hmm... tough choice.
RBS was probably my favorite Neo game of all... until I got RB2!
Both are great games, but it really depends on your preferences. Contrary to what most people say, I find a BIG difference in the combo engine.
RBS is geared more towards high hit number combos (which, incidentally, seemed to be a theme for SNK at the time - if I'm not mistaken, this was the same year Samurai Shodown IV was released as well). While a lot of the moves might be the same on principal, they oftentimes hit more times than their counterparts in RB2. It also seems like RBS is a bit more forgiving in what you can do within the engine in terms of chaining and linking moves together, while RB2 is a bit more technical.
Don't forget also, RB2 removed, or changed the controler motions for a lot of the old standby moves. For example, Terry's Power Dunk is pretty next to useless, as not only has the controller motion changed, but it can now only be used within a combo.
Graphically, I would say that RB2 takes the cake - the colors are richer, and more vibrant, and the animation seems to be a little bit smoother as well.
Basically, I would recommend RBS to those just starting off in the Fatal Fury universe, or to those who don't necessarily like FF, and instead just want something that's fun to pop in from time to time. If you're a hardcore fighting game fan, or a big fan of the Fatal Fury series in general though, I'd go ahead and pick up RB2.
