Trying to figure out what kind of 3x3 or 4x4 grow tent I should get?

I wana buy a grow tent, either 3x3 or 4x4 I wanna grow up to 4 to 6 plants... I'm getting a credit card so I can pay for everything I need so the most ill have it 600 bucks... I don't want the cheapest or most expensive bc I still have to get everything else. Which kind should I get???

http://www.accesshydroponic.com/grow-tents/

Any of the 4x4s on here are good and solid and have metal corners opposed to plastic ones that can crack easily.