The most UNPOPULAR faction in Heroes 5.

Try out your "highly praised" undead, or send Mages against the Orc... 10%? No, I haven't heard of that... Even together, they'll hardly win...

Again, it depends on the map and the time frame of the confrontation. Is there an opportunity for a rush? Well, there are a whole range of factors to consider. But I definitely know that both undead and mages are very inconvenient opponents for the Orc.