[undecided]

I hate wearing bras, (I refuse lol) so I'll do a muscle T, or a compression shirt, that seems support enough for me, but why not let them breath when you can.

I`ll second that Lotus, A tight muscle type tshirt under a normal tshirt will help flatten them out some. Up to a point, they will look like oversized pecs.
Although once you get to a "D" cup, I doubt the oversized pecs thing works too much.