It depends on what you want it for.....I have used Vital Bow Gear sights and have had good and bad luck. Four years ago I had nothing but problems, but it seems they have smoothed things out recently. The suggested sights above are great sights. If you are looking for a robust, highly designed, lightweight sight for bowhunting I suggest looking at the new G5 Optix sights.
www.g5outdoors.com I had the opportunity to see one at a show and they are awesome. I would suggest going to a bow shop and trying out as many sights as you can before deciding. Like anything else, it is all what you feel comfortable using.