You might want to narrow down the preferred configuration and features first, then choose one based on price and quality. A few things to consider:
1. Reflex or tube type. Some people prefer the less restricted field of view of the reflex sights. They also come sometimes with multiple reticles and generally allow faster target acquisition. The tube types are easier to adjust (knobs instead of wrenches) and often have smaller dots.
2. Dot size. For precise shooting a smaller dot is better. I personally prefer a 2 MOA dot, though a 3 is still OK.
3. Ease of adjustment. The very compact reflex (sometimes called tactical) sights tend to be a PITA to adjust. Usually you have to use a very small Allen wrench and there are no clicks. Larger reflex sights (the kind with multiple reticles) still require a wrench but usually have a tactile click as well. Tubes are the easiest - knobs and positive adjustments.
4. Brightness control. An important feature in my opinion. Sights with automatic brightness control tend to be too bright (at least in my experience) and obscure very small targets. I much prefer manual control.
5. Quality. This is hard to determine in advance, but reading reviews at least gives you some idea. My experience is that most inexpensive sights work fine on a .22 (though they might not last long on a larger calibre.)
One lower cost example of each kind that I have used and can recommend:
Larger reflex - Muehler, about $150 (though I've also had some $18 Chinese knock offs that worked quite well.)
Tube - Bushnell TSR-25, about $130.