I have 2x No.8
1st one is a carbon blade for whittling and carving, and the 2nd one is INOX (stainless steel) blade, which is for food prep and peeling fruit. No.8 is my favorites.
I also use No.12 for taking bark off the mid sized (2- 3 inches diametre) branches of tree logs, and carry No.6 for EDC.
Opinel is a great classic. Love the beech handles, and razor sharp edges.