[ComTrav]

EA-I remember really having fun with Caelum in SP because it was the first time I really made strategic use of weather. I was fighting Abysia, so hitting provinces with Wolven Winter before I attacked them really made a difference. And having super-easy access to very high path Air was fun.
Recently I had a fun game as Tir Na Nog. You don't have national archers anyway, so using Storm to boost air evocations is no big deal, and you can just Sing all your fatigue away.

MA-Played lots of nations here, so this was a tough call. I like ancient Greece, and MA Arco is definitely "classical" Greece, and leading Hoplites/Peltasts with Strategoi just felt cool. (Overshadowed by Elephants, sadly, but they have their own charms.) Having fun as Jotunheim (the Moose Riders are sorta fun, but about as bad as everyone says, though Giant Werewolves rock!) MA Pan has awesome units (recuperation! by a time another faction's unit gets 3-4 XP stars they're usually wrecked...) But in the end I picked Ulm, even though I figured they would be well-represented. Something about getting all the mileage you can out of 2E1F is fun, and plus, I like forging items.

LA-LA Ulm was my first blood nation, but getting a good pretender design was hard for me. (Imagine when I foolishly took Drain-2, because I was ULM, after all...) Also like Atlantis, the Inuit theme is nifty.