If it helps any, I look for something with a bumper that will protect the phone from a drop. I've seen some iPhones dropped with an Apple Bumper on them and they seem to hold up well. Right now I have an iLuv bumper on mine and it looks pretty good. Soft enough to absorb a shock, and enough of a ridge to keep the glass off the table whether the phone is face down or face up. Problem is that it's a little too soft, and sometimes I will pry it away from the phone pulling it out of a pocket.
Right now I have one of your choices on order, the SwitchEasy Trim. It's the highest rated case on iLounge, and it looks like it fits well and offers good protection in a fall. I'd also be looking to see that it keeps the glass off a table when you put it down. I especially like the plugs for the phone sockets to keep dirt and dust out. Nice touch.
BTW, I'm not a big fan of screen protectors, and I honestly believe the iPhone is made well enough to prevent scratches, so unless you are carrying diamonds in your pockets you should be fine.
All this said, I was very impressed by that Griffin case built to military specs. If you don't mind an Army theme surrounding your iPhone, it looks like nothing short of a nuclear holocaust would get through this case. The video is a hoot.
Anyway, I'm looking forward to getting that SwitchEasy case, and good luck with your search. Too bad you can't just order about 100 cases and try 'em all.