whats a good one!?

looking to pick up a new light....wanna keep it 600 or lower.....i kinda wanna try 600 cuz last time i did 400 n i kinda wanna better quality bud so i think maybe 600??? some feedback would be nice n greatly appreciated.

i had the idea to go wiht a yield master 600 watt with a switchable so i can do mh and hps......is this product on the line?????

thanks!