Gosh I guess I'm going to have to admit to being an exercise sheet-a-holic too!
All mine are wrap around.
For fit my thermalux wins hands down, and looks super smart. I think mine is 4ft6 and it fits both my 14.2 6ft rug boy and 16.2 6ft9 girl as it moulds to them.
Most used is my geldings navy waterproof fleece lined Mark Todd exercise sheet. This does not fit my mare but she has been made to wear it!
I also have a fleece Mark Todd exercise sheet which is super smart and whilst the same size as the waterproof one it fits much better but hasn't been used since I got the thermalux...
I also have a waterproof hi viz Mark Todd exercise sheet for my mare.
For waterproof exercise sheets I like the fit of the Mark Todd rugs as they are cut-away under the leg.
The equafleece ones are excellent. Hi viz waterproof fleece and they do quarter sheets as well as full ones. We've had ours for quite a few years and they always come up like new after a wash.