I'm just a civilian, but if I had to choose between glasses and contacts its easy. When I wear my glasses, my field of vision decreases significantly because the peripheral vision is lost. I can't stand just driving with my glasses on. Plus, I've lost my glasses several times while wrestling, playing sports, and other various physical activities.
On a second note, my experience with glasses and the lack of peripheral vision could work against you (if I was a bad guy.) I see a guy without glasses I assume his vision is fine. I see a guy with glasses, I might assume his peripheral vision is weak (per my expereince) and that I have a chance to pull off a stunt. I'll give you the projection of confidence, but I'd say its also a psychological disadvantage. This is all hypothetical of course, and I realize that training and awareness have a profound impact on all these things.
If you need the glasses to see 20/20, and can't wear contacts, glasses it is. If you have a choice, contacts without a doubt.