I guess what kind of mirror location bracket you get depends on your tastes and local laws.
Here in Arizona, all that is required is some kind of mirror, it doesn't state what kind or where (rear view or side view). That being said, I use my side mirrors allot and I didn't want to get something that was flimsey and would shake while I was driving down the road. Mirrors mounted forward of the doors wouldn't work for me because I couldn't see the passenger side.
I opted for these from DieTech (not my video):