On an AK, it really doesn't matter what angle you get, since the rifles are not anywhere close to tack drivers. Typically, I use the 90 degree cutter, and have had excellent results with it on everything from FALs to varmint rifles. The 90 degree cut is the least fragile cut for the effort. The only other cut I would recommend is a recessed crown, and that is very hard, if not next to impossible with the Brownell's hand cutters.
You can get the 11 degree if you want to, but every time the muzzle gets dinged, you will be "dressing" the crown. The 90 degree just holds up better.