1. What is your budget?
2. You looking for public land (lower chance of success, smaller bulls) hunt or private land (higher chance of success, larger bulls)?
3. Wilderness experience (horseback and wall tent...public land) or sleep in a lodge/house (private land) each night?
Budget will determine what options you have, but you should think about the answers to #2 and #3 so you can sort through the different outfitters/ask the right questions to see who offers the experience you seek.
Ask how many hunters/camps they have at once, how many hunters they take per season. Is guide 2x1 or 1x1. Shot opportunity %. What elevations do they hunt at. Ask for references of unsuccessful hunters and call them.
Bookcliff outfitters in western Colorado. Good genetics and some really nice bulls taken every year. Plus you will stay in a bunkhouse with hot showers as opposed to a tent.