Well, I used a buddy's Nikon a few years back for a month or so. I think it was a Nikon 550 or something, but I can't remember for sure. I remember it was around $250 at the time. It seemed very nice, and I really liked it. I had no problem getting ranges on stuff 500 yards away. Now I mostly ranged tree's or other landmarks, not animals, but it worked great. I really was impressed with it and said I was going to buy one.
I ended up never buying one, and decided to get one this year. After doing some research I just decided to borrow one again and take readings at my hunting spots then keep a journal with the ranges of my most popular hunting sights. I figured this will work great and save me some money.
I had a buddy that let me borrow a Bushnell Yardage Pro Sport range finder. My initial impression upon picking this thing up was that it felt like a cheap kids toy. It just felt super cheap. However, it worked and for what I needed to do worked fine. As soon as I went to use it, I noticed that it seemed to take a while to get range readings, and it had to be on something solid like a tree base, or a target, or a animal or something. You couldn't get a reading off of the ground or a leaf or anything like that. I also noticed that quite often you had to hold it on the object you were ranging for several seconds as it didn't seem to range them immediately. The next thing I noticed is that I would range the same exact thing and it would tell me 97 yards one time, then 100 the next, then 97 again, then 100 again. It just seemed to vary slightly on the same object at the same distance. It made me wonder how accurate it was and which reading was correct. So overall, this thing did work, but it didn't work nearly as well as the Nikon, it felt cheap, and it had difficulty ranging several things I tried to range. These are fairly cheap however, so if it's all you can afford it's better than nothing. Otherwise, I'd get something quite a bit nicer.
So those are the only two I have experience with, and those are my experiences. I'm sure there are a lot better options out there than both of them though, but I don't have any other advice as I've not used any others.