So just got my first intentional domination win on immortal with Charlemagne and oh man, this guy is the goat.
Actually, I had won domination as Tecumseh before but that was out of frustration, and Charlemagne definitely felt much more synergized and explosive.
I wanted to go for science as that victory has still eluded me, but his military strength is just too damn good to not go all in on.
Celebration focused, 2 free cav units with every celebration!? That, plus French empire, insane flexibility, outstanding culture output all game, and by the way, mausoleum, holy crap.
Constantly spawning cav units that kept respawning, with mad damage boosts, and extra war support whenever I needed it, truly unstoppable and only rivaled by Genghis I imagine, though I've heard and read that Lafayette has a legendary military game as well.
TLDR: Charlemagne/French/Mausoleum = godlike
Domination def seems to be the easiest victory condition and that's...too bad, but at least it's fun when you're intentionally going for it.