I went through the same decision process you are. I got a great deal on a 7.2 cu ft frigidaire featured in so many keezer builds. I wanted to be able have 4-5 kegs in their so that was one thing which drove me to a collar. Mtnrider's build.
Besides the number of kegs, the other consideration that led me to a collar was opening the lid. With a collar I don't need to move it away from the wall when messing inside. I've been in there alot getting things dialed in and with the towers would have needed to move it off the wall each time. That also saved me from having to put casters on the bottom. The one trade off that's a pain is it's a long way to the bottom to clean. So don't get in such a hurry to have that first beer flowing through a tap that you forget to tighten down the beer line onto the tap shank.
Nothing worse than wasted beer other than standing on your head inside a keezer to clean up wasted beer. Enjoy your build.