They came stock on my POG OS frames and I don't have any complaints.
I've never used any "pro stock" leathers (P1, Head Calfskin, Balmforth, etc.), but my favorite leather grips would be ranked:
1. TW Private Label
2. Prince
3. Babolat
4. Wilson
5. Head
Haven't tried Volkl, Dunlop, or Gamma but my friend swears by Volkl.