Ok, I've narrowed my choices down to three, but can't decide which avatar I want to play. They all sound like fun in their own ways. We'll be starting at silver.
Beastlord
Focused
3 Spawn Treachery
Silver Humanoids
The 2 Farrows
Silver eldritch (purchased on the first turn)
15 saved to upgrad humanoids to gold in the future
The beastman lord would rule the dungeons, especially rumors and legendary areas where the group can't flee without leaving behind the prize they came for. Also, we're not using the unoffical thread of answers here, so spawns work as normal in encounters. Our last campaign ended after a fight with Eliza Farrow gave a TPK, so 3 spawn treachery and cheaper spawns means hordes of bad guys to protect the lieutenants.
The Titan
2 Spawn Treachery
1 Event Treachery
Silver Humanoids
The 2 Farrows
Silver eldritch (purchased on the first turn)
15 saved to upgrad humanoids to gold in the future
The titan would play much like the beastman lord, but with some added event trickiness (Crushing Blow, huzzah!). Thaadd is cheaper than the two lieutenants the beastman lord gets, and similar in effect (faster sieges), so he'll likely be my first purchase after gold humanoids (kobolds and beastmen out the ears).
Spider Queen
Silver Beasts
Focused
The 2 Farrows
Slaggaroth
4 Trap treachery
1 Event treachery
3xp saved
The Spider Queen's dungeon presence is much weaker, though traps can be painful. However, she'll be much stronger when it comes to whittling down the heroes in encounters and the event treachery will be useful for Crushing Blow in dungeons and a Danger + Rage combo in lieutenant encounters (once the party gets Wind Pact so Crushing Blow is useless there).
Demon Prince
Kar-Amog-Atoth
Silver Eldritch
4 Event Treachery
Siege Engines
The 2 Farrows
Focused
4 xp saved
Though also focusing on the overland map, the demon prince's eldritch upgrades leaves him some bite in the dungeons, and access to Crushing Blow, Enraged, Dark Power (for Dark Priests), Ambush, and other fun events will hopefuilly go far in differentiating him from the Sorcerer King, who was the overlord in our last campaign. Siege Engines and Kar-Amog-Atoth mean -2 to a city's defense value and the silver backup will help protect at least 2 of the lieutenants. My first 11xp would probably combine with the 4 saved to buy a point of spawn treachery, for even more lieutenant protection. After that, a Travel Gem to put my special lieutenant in the farthest city from the heroes.
No matter who I play, I'll be trying to summon a bunch of comets for the Ascension plot. I'll be flat out ignoring the opportunities to siege Tamalir, as that's how our last campaign ended and I don't want to retreat old ground.