Well, I have messed with alot of different game cameras, digital and 35mm. So far, my favorite camera has been the Cuddeback. I plan on giving the CamTrakker Digital Ranger a try too as I have heard great things about them.
Building a digital game camera by yourself will save some money and it will usually allow you to customize the camera to fit your needs but there are a few problems with this idea. First, it takes some time and you have to know what your doing. Also, alot of these cameras have seperate batteries for the sensor and the camera. Usually the camera will run off of two AA's and the sensor off a different arangement. This means that the sensor will have great battery life, but the camera batteries will not last nearly as long.
I would suggest that if you want to go with a commercial digital camera that you don't go cheap. You will have alot of guys tell you about the Moultries and the Stealth Cams and they do work, but I personally don't trust them after having used them. The trigger speed is slow and this means that alot of times the deer can pass by the camera entirely before it takes a picture. It will work if you want to put it over a feeder, mineral lick, or some other food source that will keep the deer in front of the camera for a longer period of time, but if you just set it on a trail, chances are you won't get nearly as many pics as you should. Also, the battery life on these cameras isn't that great. Alot of guys will talk about these cameras having month long battery life but I never found this to be true. I could get two weeks tops and that was simply because it wasn't taking nearly as many pics. Picture quality on the Moultries and Stealth cams is also nowhere near what the higher priced models have. Granted, if you just want to know whats in the area it will work, but for the best detail... you gotta go with something higher priced.
I would suggest either the Cuddeback Expert or Cuddeback C3000 (if you can find one) or the CamTrakker Digital Ranger. My Cuddeback has been amazing and the battery life is insane. I can get hundreds upon hundreds of photos off the batteries. I am talking in the range of 800-1,000 pics! Also, the trigger speed on the Cuddeback is very fast and it provides some great quality pics.
For referance, here is a Cuddeback pic compared to a Moultrie Digital...
Cuddeback...
Moultrie Digital...
TrailMac Digital...