Without good gear it's easiest to build 2 characters.
If you have 2 keys, build a BO barb, but this isn't needed.
Blizz or Orb sorc for A1-3.
Hammerdin, javazon, trapper, or necro for A4. Might use this one for Trav as well. It is possible to do this with a sorc, even a single element one, but without gear it's really slow with cold, and without gear hybrids are slow everywhere else.
For ancients, I think the sorc is easiest so long as you have a merc that can handle a CI one. Just keep rerolling till none are cursed. If you don't have a merc that can stay alive for the duration of the fight the hammerdin is probably the best bet, but I wouldn't recommend it.
Smiters own them, but you do need a bit of gear on it, and that slows you down from getting going in the first place.