I always wonder. Are my UV's supposed to be straight as I can get them without too much stretching or are they supposed to bend like the object I'm uv'ing?

Picture for ease of description, both UV's in this are of the same object, one I made straight and the other one has a curve like the actual object, which one is right? I feel the one on the right is better than the one on the left, but would like other opinions.


This is the object I'm laying UV's out for, so you can see the curve that I'm talking about of the object