Street Fighter will probably always be my favorite fighting game. The 3DS one is awesome, it seems almost like an upgraded remake of SF2. I didn't really like any of the new fighters. I just got DOA (it's the first one in that series I've played) And it's really fun. It seems pretty simple though but i have a pretty hard time blocking (I generally prefer to hold back to block instead of having it on a button). It would be nice to be able to jump. The online on Street Fighter seems way better I never had any problem fighting somebody but 90% of the time on DOA I get an entry rejected message. The graphics on DOA are way better than SFIV. I'm Pretty disappointed in the arcade mode on DOA, since there are no endings it seems pretty pointless beating it with everybody. The chronicle mode was great but I wish you could have used more of a variety of different fighters. It was a little odd how some of the scenes were just still models while others were fully animated, but it wasn't as annoying as the still backgrounds on SSFIV. The download new suits for DOA are pretty cool. Also, I love the multi level stages on DOA, some of them are like 4 stages in one, the only thing I don't like about them is if you're going for time it's almost unavoidable knocking opponents down and it takes a little time for them to fall all the way down.
So, I'd say the stages and graphics are quite a bit better on DOA, but Street Fighter is overall better.