[gangrel]

Strap width is a function of lug width. The question can't really be answered out of context. I would say the most common width is 20mm.

For material, IMO the most comfortable is perlon because it allows for consistently optimal fit. No pre-drilled holes limiting fit length, and conformal. Next up would be cut to length silicon or rubber, if the deployant clasp is comfortable. Then soft, flexible, unpadded leather, preferably made to fit.

 

[gangrel]

I don't think width has any real impact on comfort for me, except maybe in how it might impact strap options. Perlon, for example, isn't always available in 22; almost all lines offer 18 and 20. (Some Eulit is ONLY available in 20, I think.) With a leather strap, thickness, construction, and how the leather was tanned are all bigger factors than width. There is, tho, some correlation between width and thickness, just keeping everything in reasonable proportion. An 18/16 tapered strap that's 4mm thick is gonna look really terrible. A watch head supporting 22mm lugs is probably not gonna look great on a skinny dress leather strap.

I tend to prefer loop stitching only, because then you'll get single-layer, unpadded leather. Shell cordovan works nicely; Horween Chromexcel is even softer. Not criticising other leather like barenia; I'm just not as familiar with it. I also have unpadded gator; I rather like matte finish gator. And one ostrich leg; it's dual layer, tho. I like it; not sure I love it.