I prefer the 6' leads. The one time I ordered two 5' ones (rolled leather) from a local harness maker, and for some reason she eventually sent me two 4' ones. I had waited so long for them I was out of patience & couldn't be bothered to return them & then wait again for the proper ones. In any case they cost me only $10 so I wasn't out a lot. I use them around home for taking photos, but really find them too short. There is no way I would use one of those to take a stallion into the show ring.
I prefer to have a little extra length of line to work with, just in case. Besides, I like my horses to trot out as we go down around the end of the arena & with that longer lead the horse can be out to the side, back a little, so he looks like he's stutting along all on his own.
I too like the leather leads, and much prefer the buckle over the snap. When using a snap in the show ring I put black tape around it to ensure it won't come open & let my horse loose. However, I was given a show halter and lead as a gift last spring. The lead is textured beta (flat) that has the look/feel of well used older leather. I really like it except for one thing--it has a snap, not a buckle, and to me that snap looks much too light to be counted on to hold onto a horse, even a small one. I assume it is stronger than it looks, but I won't use it on any horse that might be at all inclined to be fractious at all.