Astra Militarum
HQ:
Company command squad
Heavy flamer, 2x plasmagun
Chimera
155
Troops:
Infantry platoon
Platoon command squad
Autocannon, 2x grenade launcher
50
Infantry squad
Autocannon, grenade launcher
65
Infantry squad
Autocannon, grenade launcher
65
Veteran squad
Heavy flamer, 2x meltagun, grenadiers
Chimera
160
Total: 500/500
A fair number of bodies backed up by a pair of vehicles. Should be a pretty good starter list, getting players used to weight of fire, the importance of cover, transports, orders, and combining infantry squads.
Necrons
HQ:
Cryptek
65
Troops:
Immortals
Gauss blasters
85
Warriors
130
Fast Attack:
Destroyer squadron
3x Destroyers
120
Heavy Support:
Canoptek spyders
2x Spyders
100
Total: 500/500
Tougher than guardsmen, and with the ability to flank opponents, take punishment and keep going, and create additional units. The cryptek joins up with the warriors to make them more survivable while the spyders create scarab swarms.
This one features higher toughness, introduces to the concept of feel no pain (through reanimation protocols), monstrous creatures, jetbikes, and swarms.
Chaos Space Marines
HQ:
Chaos lord
Bike, aura of dark glory, powerfist, lightning claw
140
Troops:
Chaos marine squad
5x Additional marines, 2x flamers, power weapon (champ)
Rhino
200
Cultists
10x Additional cultists, 2x heavy stubber
100
Fast Attack:
Spawn
2x Spawn
60
Total: 500/500
This one focuses on getting in close and engaging more in close combat than shooting. The lord joins up with the spawn and can either hit infantry or vehicles thanks to his weapon combo.
With this one you would be able to learn the strengths and weaknesses of light/heavy infantry, the role a transport vehicle can play as a transport, a shield, and a roadblock. Then there is the lord with his ability to go after targets based on need while the spawn act as shieldwalls.