I have to say the Google Keyboard is my favourite.
I used to use Swype back in the day, but when Google brought out their swipe keyboard, I found it much more friendly. I recently tried the Swiftkey swipe keyboard, which I like to some degree, but the one drawback is when it incorrectly guesses the word you swiped, you have to hit the backspace, then it only gives you 3 options, none of which ever seem to be the correct word. I prefer the feature of the Google keyboard where you can long press on the central word it suggests and then it gives you a grid of like 20 words it thinks you typed. That is the best feature for me.