I say Redguard but that's really just Redguard vs Orc. Look at any legit build and orc isn't even in the running.
Generally, it's a toss up between Redguard (for stam & sustain), Khajiit (for crit) and Imperial (for health/stam). Wood elf (for mass recovery) is also an option, but orc usually isn't on the list.