Shocks:
Progressive vs. digressive valving (not getting into details here)
Body diameter
Remote reservoirs

Front shocks:
A bilstein 5100 is going to be close to stock damping. The 6112s are a bit beefier (larger diameter), which means they won't heat and fade quite as quickly (not really an issue for daily drivers). The 8112s are going to have remote reservoirs, which will improve heat and fade even more at the cost of extra hardware for a potential reliability hit. The larger diameter shocks will be slightly stiffer when cold as they're designed to be warmed up to hit their damping targets. bilsteins are going to be digressive.

I think bilstein has some similar options for the rear end, but that's simpler than the front.

I was originally split between Bilstein and OME. I think they'll be similar overall, but I haven't run either on this vehicle so I can't truly compare. Look into the adjustability of fine tuning the ride heights for each. I think the bilsteins will have different clips, while the OME (except for the bp-51) are typically done with new springs (although I could be wrong). My experience with OMEs on a past vehicle was the springs were a bit on the stiff side, so if you are running some extra weight that will help soften the ride (armor/skids/gear...).

I've opted for the ironman kit (there was a coupon code floating around here about a week ago). I'm just waiting to install it. I appreciated the rubber on all joints to keep things 'oemish' including the UCAs. It'll probably be similar to a 6112 setup.