Yeah, it's basically a prefernce thing as you said, games like smash bros and MK are fun for a while for me but as soon as the gimmick wears off for me I don't come back anymore. Personally I like the games with a lot of technical depth and skill in it, like the GG and SF series with Guard cancel, Gaurd front stepping, super exceed moves, crouch cancelling, parrying, dustlooping etc. It just keeps me coming back try to learn more and understanding the priorities and characters better. Something I miss a lot in most games.
It's basically a 2d-thing, allthough I really like the depth a VF 4 has plus I really like Soul Calibur ll for the fast gameplay and tough AI which can lead to maniac battles on higher settings.
I still need to check out DOA Ultimate, allthough I'm a little biased because of the bashing that goes on about the presumed button-mashing in the game, I need to give it a fair chance IMO.
I never owned a dreamcast, it was never populair here so it came and went very fast.
Lots of nice fighters available for the dreamcast....
Maybe try to pick up a second hand one sometime.