I've tried all three (Compression Bodysuit, Tanksuit and Body Shirt). They're all the same from the waist up, very comfortable and all have their advantages.
Compression Bodysuit - I found the most comfortable. I think I'll get the one without the zipper next time, I found it's easier to just pull down. Pulling it down wasn't nearly as weird as I thought it would be in a public facility.
Compression Tanksuit - If sit-down business is your primary concern, then you'll want to get the Tanksuit. The snaps make this real easy. I did find the snaps awkward when I had stand-up business though and opted to use the stall. If you are more concerned about stand-up business, then go with the Bodysuit for its fly!
Compression Body Shirt - If you are worried about both situations, then go with the Compression Body Shirt. It's just as comfortable and has plenty of length for tucking (and I'm 6'1"). I'm not too worried that it would become untucked, but I do like that there's no way for the suits to become untucked.