i honestly wouldnt feel comfortable saying orcs are better than humans.
Here's a theory ..
Early in the game's history the benefits of lust were realized.. and they are large benefits .. at that point, people kicked humans to the curb and collectively agreed they were inferior.
The game has evolved a lot since then ... people have been playing exclusively with orcs (generally speaking) for the overwhelming majority of war2's history.
Developing game play/strategy for humans has pretty much been non-existent. Which is one of the reasons i dont think you can say with certianty humans are inferior.
Another reason is because there have been/are some TOP players who use humans against other TOP players of pretty much equal skill level... I think most would agree Viruz, Shotgun, and POSCOW are essentially evenly matched assuming they all have the same level of activity. and viruz wins with humans.
being a human actually has a couple advantages if you think about it... You spend zero time bloodlusting, which gives more time for other areas of production/expanding/defense.. invisible mage is 100% effective.. orc's haste is not always a guarantee.. and if you play humans right, it's easy to "mind fuck" your opponent. it is extremely aggrivating/stressful playing someone who does sneak attacks with knights, then evades as soon as you lust your ogres .. it takes a mental toll on the orc player.