Best Unit in the Game... Any thoughts?

[Aleph]

Pound for pound:

Gold - I'll second the "quality recruitable anywhere sacreds." In particular, Mictlan with F9/W9 and Lanka with E9/N9 can be absolutely devastating from year 1 through the endgame (sure, counters will come up later on, but they are still among the best basic troops, and numbers are king in Dom 3). Jotunheim's sacreds are horrifically powerful, but they are capital only and so favor smaller game types.

Magic - Dakini. Great access to air personal enchantments, flying, blood vengeance... a hunter, forger, raider, and SC chassis for a song.