I used Flex T9 before switching to SwiftKey - still love Flex. I don't think anything beats Dragon dictation - but unlike other keyboards that only get close, SwiftKey does give three guesses and my experience matches Emblazon's - one of the choices is correct.
SwiftKey has three advantages for typing:
Word erase - swipe right to left anywhere across the keyboard
Arrows - with the X version you can have them always on, but I don't - tap 123 then tap symbols key next to it - because I don't use arrows often, but when I do, they're a livesaver
Word prediction - you lose speed typing instead of swiping but then you get it back when you can tap the next word it's predicted - often several words in a row. And if a predicted word is only close, choose it anyway, then tap delete a few times to trim the last few letters from the word, and often the auto-complete will give the word yu wanted - then you're back to word prediction.
For me it's faster than Flex T9 but I'd never say a bad word about Flex and think these sort of preferences are just that - preferences. If I have something long and complex to dictate, I often just go back to Flex before even trying because I know it'll nail it.
For a good, straight computer keyboard, I also recommend Hackers Keyboard, free in the Market. Sometimes when I just want type out something specific and highly technical, I'll switch to that and not let all of these other fancy features get in my way.
Right tool for the job, you don't have to use just one.
By the way - free in the Market and many other phrases I use - SwiftKey learned from me, I can interject that phrase with 4 taps. Nice.