Street Fighter has always been far more technical then Mortal Kombat (spacing, footsies, frame traps and block strings). But Mortal Kombat was usually for people who like more superficial and surface aspects to a game (gore, over the top action, etc), which honestly, nothing wrong with that at all.
That's not to say Mortal Kombat doesn't have a technical side to it, it sure did, but it just never reached to the level Street Fighter got in all the years I played in the competitive scene.
However, the MKX is actually pretty tight, they did a surprisingly large amount of revisions for it. It's definitely a technical contender now.
Street Fighter I like for nostalgia more, but dude MK gets me hype. Like almost in a sexual way. I just love that so much. Street Fighter just doesn't have nearly the appeal MK does. Did you know they are coming out with some more movies? It will be much much more brutal and violent. The guy who is directing is the same guy who did the Saw movies.