After much research, I bought a Vortex Sparc w/ a 2 MOA dot and have been very pleased with it. It is rated to handle a 375 H&H's recoil and a huge plus is that it comes w/ several mounting options included, lifetime warranty, and won't break the bank. The Red Dot is bright even at it's lowest setting, holds zero, and is an extremely tough little Red dot. The Eotech and Aimpoints are great and of high quality, but will come with a higher price tag. If I were not going for the Eotech or Aimpoints my choice would be the Sparc. The Bushnell TRS-25 is another you may want to look at with good reviews, but I don't know about it's toughness in handling prolonged heavy recoil. If you want to go with a reflex sight Burris and the aforementioned companies are good as well.
I just picked up an outstanding Aimpoint Electrodot 4 with 4 different reticle patterns, both red and green and has a very large, rectangular viewing area. It has an aluminum housing which makes it rugged, clamps to a picatinny rail and both red and green reticles are adjustable and VERY bright...plenty bright for outdoor viewing. Yes there are smaller dot sights - I have a Tasco Optima which was the original small "window" type dot sight and it's a VERY good sight as well but I've found when mounted on a pistol it's hard to pick up the dot quickly. The larger Aimpoint window makes picking up the dot very fast.