firstly noob that sig image is too big
second orcs are awesome at solo
Demolishers: They combined with a farseer can wreck hacoc on any town from any race in the game
Bezerkers: A great aa and if protected can use bezerk quite good and not take too much damage
Windriders:have a piercing attack and a fairly high attack rate so they can beat any air unit in the game.
Raiders: pwn any type of magic and with pilliage you get a ton of resourced from buildings
Grunts: one of the most essential units in the game and with it being a starting unit, an early grunt rush = gg
Shaman: Bloodlust speed and attack Purge destroys summoned units and lightning shield takes out any and all ranged units
Troll Docs: Healing ward no need to stop your attack on the enemys base Stais trap stuns enemy so in a tight spot you can take advantage
Sentry wards: Sentry Wards last 10 minutes! The Witch Doctor comes with this spell initially, so build one and place Sentry Wards around key locations such as Fountains, enemy towns, enemy mines, key traveling points on the map, and your town, in order to spot invisible units. If you're having trouble with Night Elves using Shadowmeld or Blademasters using Wind Walk, the Sentry Ward is the perfect solution.
Tauren: One of the best meat shields in the game...if your mainly going casters get a tauren or two for protection.
and yes the spirit walker sucks ass