Underarmour all the way. I have been wearing a black short sleeve shirt for well over a year and I train at least 10 hours a week. I have a white short sleeve and a white long sleeve though I made a mistake with the long sleeve and bought the cold weather so now I burn up when grappling, but this is good for training.
Hey: just want to say thanks for the help again. The rashguards are doing exactly what I'd hoped they would.
The WalMart ones I saw were all "Starter" brand, fwiw.
Stay away from stuff with a ton of decals on them. They will always peel fairly easily.
Evidently it depends on the WalMart, whether they have UA or not, or rashguards at all (there's another in my area that had none at all). But there is a clear diff in quality, agreed.