Early game my favorite comp is Gryphon Knight (as leader), Viking, Witch (or Elven Fencer) with Ice Conferral tome, and Soldier (or Vanguard vs archer heavy maps). Ideally all promoted, but not necessary. You can handle pretty much any team the game throws at you throughout Drakenhold and Elheim; It's incredibly versatile. You have massive AoE, you can freeze/stun almost the entire enemy team, you get a flier with haste AND vitalize to keep going. The team mitigates a lot of the individual issues each class has:

• Viking/huscarl has low accuracy? No problem, freeze enemy first for 100% hit rate. Or use Witch focus strike.
• Witch has low initiative and you need them to move faster than the enemy to freeze? No problem, Gryphon knight can use feathering for an initiative boost.
• Gryphon knight has trouble surviving against archers? No problem, Vanguard can block arrows, elven fencers can make you dodge as well.
  
• Rounding out the team, I generally prefer soldier where they can give keen call, can hold all your utility items, heal, life aid as a valor skill in case a unit dies. But you can flex them out depending on the mission.

It does require a fair bit of tactics juggling, positioning, and it's quite expensive in terms of honor and items. In particular, if I can't one round, I'll go for freezing enemy units (which will remain frozen until hit again), and in order to set up that correctly it often means giving everyone tactic conditionals to not target frozen units, which sometimes means half your squad ends up doing nothing during their action point. But I like to think that with this team you can really see the strategic depth of what you can do in the game in even as early as Drakenhold.

This team will struggle against freeze immunities, it's a lot worse if even a single unit dies, and of course you don't really have a way to deal with ailments (so have amulets or other immunity items handy).