I can't tell you which camera to buy but from having my own here's some suggestions on the features that matter:
A good triggering system is important - you never get to see how many animals your camera will miss. All cameras miss some triggers but try to get one with a reputation for reliable triggering, the difference when you put two cameras side by side in the same spot can be remarkable.
Speed of trigger - this is really important for me as you need a really fast trigger if you are to catch useful images of the animals. Be careful as some cameras have quite a fast trigger time for still images in daylight, and they will quote this time in the advert, but for video in the dark the trigger time can be quite a few seconds. This is more than enough time for an animal to walk away leaving you with an empty frame. So, get as fast a trigger as possible and try to check that the camera offers this fast trigger across stills, videos and in dark and daylight.
Realistic expectations - most cameras work well in the 10 - 25 foot range, maybe 40 feet max, and to expect them to work over more than this is pushing your luck so positioning is critical. They also often require careful aiming and this can take a while to get used to.
Image resolution - this is a cheap and easy selling point for the manufacturers but in truth you don't need a lot of resolution as this isn't a photo for the family album, it is just to see what is about. In general lower pixel counts can work with less light so there may be advantages with lower pixel counts so don't let this sway your buying over more important features. I think Reconyx, who make the undisputed Kings of trail cameras, are still using 3 Megapixel sensors as they market their cameras on the things that matter, unfortunately there's no way I could afford one.