I like to wear "wife beaters" under my shirts. They give me a comfortable layer of air between my skin and the shirt. I seldom get any sweat marks on my back during work(office), and i tend to sweat a lot. But, they aren't very sexy.
I use a norwegian brand called Dovre. Unfortunately they are rather expencive. 31 dollars a piece.
WOW, I remember in Germany my preferred brand was Schiesser, they are also very pricey. Here I wear only Hanes and FotL, can't beat the price. You should consider to buy yours here in the USA and have them shipped to you - you save a lot at $31 an A-shirt!!