I'm a keyboard addict. I own Smart Keyboard, Swiftkey X, and Flex T9 (plus Swype does indeed come preloaded). Swiftkey was my favorite until Amazon had a freebie for Flex T9, and now I can't live without it's swipe feature, which is basically the ability to run my fingers over the screen somewhere near the letters I want and have it figure out what I mean. It learns fast and seems to put my words ahead of it's own words.
That said I'll give Swiftkey another try, I really do like how smart it is (I love that it predicts a word before you have typed anything at all!)....if only it had swipe words capability, it would be my choice.
But it's slow to have to make a decision for each word before having to type the next word. With FlexT9, I often swipe all my words very quickly and then fix the two or three it got wrong, which it does really well because it offers suggestions for highlighted words.
So here's my advice. If you have a bionic, try the built-in Swype. If you like it but maybe want more features (I don't know, honestly) try FlexT9. If you want to tap instead of swiping, try Swiftkey.
Lisa