If you're not worried about money, then it's a no brainer. Go with the ATI, from what I've read they are the best T5 fixtures on the market. Again, I have no first hand experience but if you read a little bit about T5s you'll see that ATI is hard to beat. They have almost double the PAR of TEK lights in some situations and overall i think they'll outperform a TEK in any category you're looking at. Now, a TEK will probably grow anything you want but the ATI is definitely a superior unit.