I've used some of the Simmons cams, had 3 and they worked ok for about 2 years then quit working completely. Even for the price they don't offer much for features, i'd stay away unless you get a real good deal. They only hold 4 AA's and seem to die fairly quickly.
I've tried a few Wild Game Innovations cams, They have so far been pretty dependable, my first two are going on 4 years and still going strong, i got two more this year and we'll see how well they last. As far as features/picture quality they are ok at best. You have picture or video mode, quality isn't great, trigger time isn't great, reset time isn't great, but hey, they're still working. With their slow speeds though you need to point them down a trail and have things trigger them coming or going in front of it. If you have it watching side to side on a trail you'll either get pictures of nothing or at best a deers ass as its walked by.
Moultrie Cams, had one this year to test. Quality and features seemed good, but the trigger seemed almost a bit too sensitive. i could probably turn it down, but i've always had hundreds of pictures of trees moving slightly in the wind to sift through to see any animals. They seem decently tough, had it knocked off the tree a few times by a bear without any harm untill the third time it bit through the lens on the camera. It still worked even without the protective lens, but eventually water got in and shut it down. Once i got it home and it dried out for a few days it's back to working order again. i figure if i can replace the protective lens i'll be good to go again.
StealthCam, so far these are my top pick. They've got enough features to make them do what you want them to do, take good quality pictures. Their quickset makes it easy if you don't want a specific setting for trigger times and such. They seem to work very well taking pictures of animals, but not soo many of weeds or trees shifting around. I have only had them for 2 years, so i can't say long term how they will hold up, but so far so good. They also seem pretty consistant for picture quality and features between price levels. I think i have a spread from p18 up to p36 and there's no practical differences in the pictures themselves.
All of them besides the simmons took 8 AA's and i put them out in the summer and they usually last untill hunting season, with the WGI cams seeming to fade away a month or two before the stealthcams.
If it came down to it i wouldn't hesitate on the moultrie or stealth if it was a good deal. WGI would have to be a real good deal for me to get more with their picture/trigger quality, and simmons would have to be practically giving them away for me to waste any more money on them. There are other brands out there, but i haven't tried them, so i can't really compare, and with any brand, they have high and low ends of the spectrum.