I agree with Anonymous (concerning a good instructor over a style) 100%.
To add my two cents, and my standard canned response...
What is available within the area in which you are willing to drive? You could have your dream style revealed to you only to have the nearest school of instruction located on a different continent, which would do you no good whatsoever. If you're truly looking for a school in which to train, narrow your search down by what is within the previously-mentioned area, attend classes, talk to teachers, talk to students, don't sign any contracts, see how they train, then make a judgment based on that.
If you still require assistance in what you should take after performing all your due diligence, come back with more specific questions and others here, including myself, will be more than happy to help.
EDIT: Also, you realize that when taken for martial application, Taijiquan is not performed slowly, right? LOL