Hanes seems to take the cake when it comes to undershirts.  I purchased the 4 pack of black/grey, and they are priced perfectly.  Be aware that they are 100% cotton.  It seems as though the Washed Black Heather undershirts have the polyester mix, and the solid colors are 100% cotton.  I've noticed that some reviewers are upset that these fit snug, but they are undershirts and are designed this way.

I dig that the undershirts feel soft even after washing, and they don't grab onto the outer shirt.  The shoulders aren't too long, the collar doesn't stretch out easily, and they are long enough to tuck in without them constantly pulling out.  The black looks good after washing also, which is a big thing for me.  I hate having a black undershirt thats faded, as it looks odd if the collar is seen with a nice buttoned polo.