I used this site to help me choose a light. I ended up getting the Current USA Pro but only because i found it on ebay for 2/3 the price. Not sure about the PAR levels on those lights. What kind of plants do you want to grow?
You could go with a finnex fugeray planted plus. or the ray 2 or the normal fugeray depending on how much light you want. The 20" fits across the whole thing. I have a 16" fugeray for mine and it fits on the opening in the lid.