I think it needs to be noted as saying what sort of warrior.
The orcs are, as I see it, magnificent heavy infantry. Physically they are the most robust of all the races, save the largest khajit, they almost universally have experience in smithing so they can maintain their kit and their way of life lends itself to being capable warriors...as the incapable rarely have children.
The Nord's are ferocious warriors, capable of holding a shield wall or charging an enemy, I see them as more medium infantry and the best for fighting on mass...as getting a large amount of orcs together is hard due to them not having a central province, and Redguard prefer singular affairs.
If you want to raise a legion of hardy fighters, go Birds.
The Redguard are the most talented, which I take to really mean best. But they are light infantry and are better as skirmishers and loners than in a big group. I think on pound-for-pound base they are truly the best though.
If you want to have an amazing bodyguard or a team of hardcoe champion level fighters, go redguard.
So yeah, orcs are heavies, Nords are medium and redguard are light. Orcs are solid and strong, Nords sre fierce and flexible, Redguards are masterful loners.
I would imagine Nords to be like a pack of wolves, an Orcis like a crocodile and a Redguard is like a jaguar.
That is my take.