None of the above I would say, since none of the three ships fit all three descriptors; I would call the XI Enterprise sleek and streamlined, but only to the XI Enterprise, and I wouldn't call any of them sexy (I would give that to the B, D, and E to varying degrees).
But since we ARE talking about the TOS ships, then the Star Trek XI Enterprise wins in any contest of aesthetics, provided we're talking about the exterior. And interiors too really, barring engineering.
But since we ARE talking about the TOS ships, then the Star Trek XI Enterprise wins in any contest of aesthetics, provided we're talking about the exterior. And interiors too really, barring engineering.