Depends on what you like, really. I love my Eteks and my Ion's, which are relativly cheap and easy to upgrade to tourny level. You don't need to buy an expensive gun to be good
Your best bet would be to speak to your team mates, or fellow ballers you associate with and just have hold and feel of the markers they use, this way you will get a better understanding of what you like before commiting your hard earned cash.