Paths of Blood

[Aleph]

And I forgot to mention Rangers for LA Ulm, arguably the deadliest ranged troops in the game, and decent melee troops to boot.

I think MA Abyssia is a nice introductory blood nation. Their magical pyrotechnics and heavy infantry are quite brutal through their affinity for fire (awesome to be able to toss fireballs into tightly packed melees without a care), while their Demonbred make excellent blood hunters (and everything else as well, but that's another story). You have a lot of solid non-blood options to play with, as well as the best blood skills of their era, but without tons of blood uniques like Lanka or Mictlan - while their national spells are amazing, if you rely on the nationals you'll learn less about Blood overall.