Tekken is good, but one of the problems I have with it is that most the match is spent trying to get the other guy in the air... and once get thrown into the air, you're just about finished. I understand that this is also the reason a lot of people praise Tekken as THE fighting game - because it demands a certain level a perfection on your part or else you die. I dunno, though... it just seems a little bit wonky to be trying for an air combo the whole time (it's a little like MvC2, but nowhere near as broken or glitchy). My biggest problem with the game, though, is that it's very stiff and feels 2D. Not that 2D is bad or anything, but a 3D fighter should be more 3D-ish, and that means it should be easier to sidestep/strafe around the arena. You can't do it smoothly in Tekken... if just feels like the game is locked into one plane, which kinda sucks.
Soul Calibur, on the other hand, is an extremely free flowing game. 8WR is probably the greatest thing ever put into a 3D fighting game. It makes the game flow so smoothly and makes it ever so fast. This is the main reason I like the game - 8WR. 8WR makes dodging, strafing, and even things like feints possible. I feel SC is also more of a mind game as well as psyching your opponent is a huge part of the game. Doing something like pretending to go high, then going low, and then cancelling that into a throw is great.
So yea... I think Soul Calibur is more fun.