my fav race, followed by 2'nd, 3'rd and 4'th:
1) Elves. The 1 less food at start is painful. But choosing which units to damage is awesome. And each unit has consecutive iniviative (1,2,3,4). The archer/warrior combo is nice. First deal out damage then finish the damaged units with the warriors. Also completely adore the pegasus riders... 2 initiative with quite nice speciality.
2) Humans. One reason, otherwise I hate them (Too bulky and not very smooth killers. They focus too much on taking down big units and in our games being swarmed by many weak ones is the real threat) the +2 strenght development. It is SO nice to protect your strongholds! Ok, the horsemen which lets you draw strategy cards are also explicitly awesome.
3) Demons. Attacking with 8 berserkers and having 2-3 specials is devestating :S Also fleshrippers having 3 health is a massive pain in the ***!!!
4) Undead... well, the resurrecting is quite fun. But when your poor necromancers die its so annoying to get them back. And the initiative feels so blunt. And their last strongest units feels not as interesting as the others tbh.