The Orks are, obviously, the most fun to play. Well, how could they not be? The Ork race is, in the Warhammer universe anyway, the life and soul of every party. Of course to them a party means bringing along four tofive hundred mates, needs some high calibre automatic weaponry and, if possible, orbital bombardment, but still. You get my meaning.
The one real problem I have with the game so far is that the Eldar play so differently from the other three races. The Orks might require one more resource than the Space Marines or Chaos Marines, but that's not that much of a hardship. Instead of building a turret next to your listening posts (for no extra gain), you build a Waaargh! bannerthat ultimately adds to the power of your army. The Eldar, however, start with the puny Guardians and remain with the puny Guardians until and unless you research the different Warrior Aspects available. Their tech tree is different from the one the other three races share.
It seems to me that if you're going to have four unique races then they really should all be unique - or all the same.