Salt Mines is in Vaegir territory, and Zendar's a pain to get to once you leave that area. +1 Vaegir
Both get knights. -0-
Vaegir gets mounted archers, Swadians get ground pounders with crossbows. +1 Vaegir on travel speed, +1 Swadian on power. Effect: null
Swadia has most of the golden trade triangle in it. +1 Swadia.
Vaegir has 2-3x the amount of Dark Hunters in it. +1 Swadia.
End result: Doesn't really matter, the differences are cosmetic with some minor annoyances in one way or the other, with Swadia taking a very minor lead in my mind.