I recently downloaded the SwiftKey X app from the Android Market for $3.99 after many recommendations to do so. It was definitely worth the $3.99. I love it and use it all the time now.
Its extremely easy and fun to use. What makes it fun is to see how it actually predicts the word that your going to type next. After you use it for about two days it will actually know what your going to type next almost better than you do. I found it taking me almost half the time to type up a text then it did using the stock Android keyboard my phone had build into it. The only keyboard that i found was better at typing faster with was the latest version of the Swype Keyboard. Both keyboards have their ups and downs but I digress.
There are four different themes that this keyboard has and each is very unique so you should be able to find one that you somewhat like. The special keys layout like the numbers and plus sign etc. is very appealing in this keyboard and by far my favorite out of any keyboard on the Android Market. The keyboard itself is very responsive and accurate when your typing which makes it easy to type fast and accurately.
The only problem i have with this keyboard is that there is no way to turn the auto prediction of every time you hit the space button which can get very annoying at times. But this keyboard app is definitely worth $4 and if you wanna try it before you pay for it then you can download the trial app off the Android Market for free.