There is a big gap between categories here, but I think that spotting scope selection truly gets interesting once you arrive to the $700-$900 range, so it is justified.
Once again, I will start with the smallest objective lens diameter and move on up:
Nikon Fieldscope II 13-30×50 is a gem of a spotting scope and it can double as a hand held monocular in a pinch. Optically it is superb and easily the best 50mm spotter I have seen. Be mindful of short eyerelief though.
Vortex Recon 10×50 and 15×50. These are an almost new category of devices. They work fine as both a spotter and a monocular, except they come with a handstrap, so the monocular functionality is much easier than with any other small spotter. Both configurations are available with or without a ranging reticle (I’d go for the one with a reticle). Optically these are excellent and eyerelief is quite a bit longer than on the Nikon.
Pentax PF-65 ED. This the spotter that I use for my purposes. I think this is the best overall compromise of size, weight and performance. It is most commonly available with the XF zoom 20-60x eyepiece. However, this spotter really comes to life with one of Pentax’ spectacular XW eyepieces. I would recommend you check out XW14, which works out to ~28x magnification.
Hawke Endurance ED 16-48×65. This spotter is a cheaper than the Pentax and similar optically. It is, however, notably bigger and heavier. Pick your poson…
Vortex Viper HD 20-60×80. I do not have too much mileage with this one, but it is a nice spotter.