I like the under-armor compression stuff. Sure, you look like one of "those guys" because the shirts leave little to the imagination, but the slight compression does wonders for me.
I used to only wear wife-beaters (I love the feeling of contact with the bar or bench). But I was swelling during and after workouts badly (shoulders and forearms mostly). I got to 400 mg's ibuprofin pre-workout, 400 more during and 400 more afterward.
Post compression shirt, as long as I keep it on about 1-2 hours after I'm done, I need no ibuprofin!
P.S. Nike makes a tight compression shirt that is a little bit stiffer than the under armor one.