Kirk's wraparound uniforms
weren't made of velour like the regular uniforms. They were all made of a double-knit wool and were constructed to be a little shorter than a normal shirt cut.
In fact, the second season wrap had suspenders and hooks that attached to the trousers, see on a screen-used tunic here
As for my preference — velour or double-knit synthetic?
I used to prefer the velour, but as time has gone on, I've come to prefer the double-knit because it's smoother and fits better.
My favorite uniform, however, is Kirk's first season wraparound with the scrambled eggs on the shoulder. In fact, I own replicas of both these uniforms:
by Clark "Kal-El" Kent
, on Flickr
The regular duty uniform is the high-end, screen-accurate replica from Anovos
While the wrap is a fairly good replica made by a costumer — the braid and insignia aren't as screen accurate.