Get the one that fits you the best! Semi or o/u is up to you really - at our range just as many shoot both.
The XT is a very nice shotghun and would serve you just fine. However, given the price tag it may be overkill for a newbie.
Head out to your range, see what other guys are shooting and maybe ask them to shoulder or shoot a few of them. You will quickly find what you like, if you are considering the different shooting sports you may consider a sporting model as well.
Any of the "B" guns will do just fine and help retain some of their value.