It really depends on your price point. You can get a cheap fixture made by Odyssea, they are decent but you will want to replace the bulbs ASAP, I have a friend that bought the 72" version of this light and he loves his. These lights look good and come with a nice digital timer so you can set it up how you want.
A more expensive option would be a Current USA fixture or maybe even a TEK fixture, but your looking at twice the cost of that Odyssea fixture for these. I just recently got two used Current USA fixtures and they are awesome! My only complaint about them is they have cooling fans in the and I can hear them, but they are still new so I probably just need to get used to it.
All in all it just depends what you are able to afford to spend really. If the sky is the limit I would get one of the top name brands like TEK or maybe even try out LEDs. Since I'm always on a budget I try to get my things second hand, always get a lot better deal this way. Like most hobbies, aquarium hobby equipment just does not retain value, so I would look around locally and see what you can find first, you never know you might run into a great deal!!
If they don't see this post and reply to it, this guy Hoppy, seems to be the lighting expert on this forum, so you may want to send them a message and see what kinda advice they offer.
Hope this info helps, let us know what light you decide to get!