I do well with humans, I don't know, I just seem to do better with them then other races. Against night elves, I got footmans with Paladin, Defends owns the archers, and try to quickly advance to knights. Paladins aura and heal spell work wonders with footman rush, and resurrecting knights late game is amazing. Against orcs, I would get Archmage with a mixed group of rifles and foots. Move on to gryphons as orc is weak vs. air. Agiainst Undead, I like to get rifleman, and pair with an Archmage or Blood Elf (the flame caster guy). Rifles, then mortars to deal with those pesky undead towers. Against other humans, you have to see what they are getting. Start with foots, then go knights if they rifles and gryphons, or go to gryphons and mortars if they melee. As far as human spellcasters go, I usually get a few priests, sorceresses are reserved for when I want to get tricky with my hero.
But I don't play too much melee...