Long Post, but you asked.
I use Moultrie, Wildgame Innovations (WGI) and Primos. A total of 21 trail cams.
I'm serious about my deer and turkey hunting. I keep my cameras out year round.
The first two I bought were WGI 1.2 mp IR. They run on 4 "C" batteries. Been using these same two cams for about 8-9 years. They just won't die. I even left the cover of one open during a heavy rain. I thought that had killed it. Brought it inside for about a week to dry out and it came back to life.

Resolution is not great but for $75 for both cams I wasn't expecting more than I paid for.
Next up are the WGI Micro Red 6 and Micro Red 8, 6 mp and 8 mp. Been buying these for the last 5 or so years. The Micro Red 6 seems to last longer than the Micro Red 8. I'm still using all 7 of the MR6's and had 1 MR8 die, replaced under warranty I have 5 of the MR8's. Really good daytime pictures and better than expected night pix. I found 3 of the MR6 and 2 of the MR8 cams on closeout at Academy back in March. $50 for the MR6's and $60 for the MR8's. These cams run on 8 "AA" batteries and have an internal battery that holds date/time/cam setting while changing batteries. They will also take a solar panel. Battery life is about 3-4 months taking 3000-4000 pictures on a 16gb SD card.
Moultrie M880 and M990i. Same camera except the M880 is a red flash and the M990i is a black flash and also has a picture viewing screen. All around great cameras. I've owned 3 of the M880's for 3 years and 3 of the M990i's for 1 year.
These cameras run on 8 "AA" batteries and have about a 3-1/2 month life span on fresh batteries taking 3000-4000 pictures on 16gb SD cards. Will take a solar panel. Internal battery backup same as WGI MR6 and MR8.
Primos Ultra Blackout. Bought 1 NIB last month. It was dead out of the box. Exchanged for new camera. Replacement lasted about a week. Took it back to Bass Pro for another exchange. Keeping my fingers crossed on this one. Your luck may be better than mine.
Skrazo, I'm using the 3 M990i cams around the house to keep track of the comings and goings of others in areas not easily hooked up the home alarm system.
Up at the farm I have several cameras that are dedicated to catching trespassers as demonstrated by the last picture. I've had people successfully prosecuted by using trail camera pictures. Don't know who these 3 are. Maybe one day we will cross paths.
Class III