>>1942337
Factions' difficulty spike when you hit the mainland is infamous due to the enemy level jump. My experience playing GW1 even back in the day was that it wasn't too hard most of the time, but there are build/skill checks that tend to hard-stop your progress until you figure it out. The ones that always come to mind are Elona Reach and Tahnnakai Temple.
Kaining City is probably my favorite region in the game, it's the kind of poverty-stricken urban hellscape that wraps back around to being comfy as fuck.