1. Orc/Orsimer
2. Nord
3. Redguard
4. Imperial
5. Wood Elf/Bosmer
6. Dark Elf/Dunmer
7. Khajiit
8. Argonian
9. Breton
10. High Elf/Altmer
Basically, my theory behind this subject is the closer they lean towards combat, the more "mercenary-ready" they'll be. Contrarily, the closer they lean towards magic, the less "mercenary-ready" they'll be. Stealth is a neutral factor, and the stealth races leaned more towards combat won out over stealth races focused on magic.
Why did I see mages as weak mercenaries? Uh, I don't know. I just don't see that happening. It's like looking at a picture of a dolphin driving a convertible near the beach.