Swiftkey is great...but I just can't leave Swype. In a perfect world, Swiftkey and Swype would hookup and produce a keyboard with the great features and predictions of swiftkey, with Swype ability built in.
At first I was bit clunky on swype and didn't really like it, but after a while I got used to it and now really fly. I don't know if it's because it learns my typing style or I've just become better at using it, but many common words are essentially just memorized gestures...and while not nearly as good with predictive text as swiftkey, it does learn your commonly used words to keep typing mistakes at a minimum after a while.
Pretty much anyone here will vote for one or the other, which ever one is "better" really depends on your personal preference. Both take some getting used to as far as being able to type quickly, but once you've become accustomed to using either style, you'll probably have a problem going back to anything else.