As far as I've "heard" Tekken and Virtua Fighter are quite popular in Japan. Arcade scene and all.
Dynasty Warriors is pretty popular too, since this is why Xbox 360 players can't seem to get any of its expansions now.
I'm beginning to feel like fan service attracted players to SC as well. Aside from Taki's "everything" visible from her outfit, many people loved SC2, because of Link only. Not one mention of Spawn, and Heihachi is a Namco character, so no surprise there. If you hear anyone say that they loved SC2 more than the other games, more than likely the name "Link" will be in that same paragraph, especially in Japan, since they LOVE Nintendo.
Personally, SC was doomed once they introduced guest characters, because that equaled massive fanservice. It brought the wrong type of consumers into the mix. Usually those that expect more than the amount of fanservice in SC2 to be in there more often.
Which I understood deeply that SC toning it down for SCV was the best idea they could ever think of, even though they tried it with that horrid Ivy ad even though Voldos was better.