LIJ,
have you checked out the "Halvarsson" line of leathers? I really like their "classic" stuff, like the BC Master, BC Iron etc. When I was looking at those side-by-side with the Triumph jackets at a dealer in Norway, the Halvarsson stuff appeared to be of thicker and better quality leather. (Even though some of the Triumph jackets were very cool looking)
Myself I got a 2-pc suit in goat nappa, made for Yamaha in Sweden by "Cockpit Clothing Company" , decent stuff at a good price. And this year I bought a more classic looking jacket (in cowhide) that I can wear also when not riding.
As for the leather quality of cow vs other species, I've heard that kangaroo hide is very tough - but pricey, and mostly used for gloves. Goat is tougher than cowhide of similar thickness - but cowhide used in riding gear is usually thicker.
Also I'd say quality of the zippers, seams and the actual quality of the leather used , is much more important than what kinda animal it is from.
Myself I prefer cowhide before goat, but that has to do with the more "substantial" - and at the same time, softer feel.