Normally I tend to play RTS games were you can both command and play as the units in battle like Age of Wonders and Battalion Wars.
Halo Wars does seem interesting though and if there are five armies instead of just the UNSC forces, covanent, and flood it would be nice to see how each fares, here is somthing I would expect to see if there are five armies.
UNSC- most well rounded, units are basiclly any weapon wielding guys you have seen in the FPS games.
Spartans- aside from most soldiers having recharging shields infintry would most likey be the variations we have seen in Halo 3.
Flood- most likey just kill with a spore and take them for more units.
Elites and Brutes I have no idea for expect maybe Brutes have the best strengh and Elites are just faster. The varaitions of Elites like Combat and Assault would mainly be in along with the kinds of Brutes seen in Halo 3 like the Brute minors and Brute captains and Cheiftans.
Age of wonders was a good RTS when you enter a battle you get to choose automatic or move all the guys you want that you can and choose 1 abitity they can use like archery or magic per turn and have them gang up or attack specific units. Also have them support each other or sacrifice themeselves, as well there are hero units that get more powerful over time and can equip found items. Also each of the 12 races has its own mega unit like the humans have an air galley that can shoot javalins while the undead can summon the grim reaper and the elves have a nature elemental that can keep healing and crushing all in its path.