^i would consider other options if I hadn't decided that I really like my Burris Fastfire III.
It is small, lightweight, waterproof, still on its first set of batteries after 6 months of use. I expect batteries to last for at least another 4-6 months, at which point I will change the battery. Dot is small enough to hit chipmunks with it inside of 50 yards. I like its automatic light adjustment and brightness settings. Great in low light or full mid-day sun.
At the moment it is mounted to my Henry .22, when deer season comes around it will be coming off the Henry and going onto a Marlin 336. You didn't mention your price range, I managed to get my FFIII 3moa red dot for a little over $220, most places are a little higher than that. For a price I consider very "reasonable", I have been very pleased with its performance and quality.
Just a note, this thing will sit so low that it won't clear your front sight sitting on the top rail. I have seen a number of pictures of people using a 45 degree offset picatinny rail to attach and they seemed pretty happy with it set up like that.