Yeah, I'd say Ul'dah's more dangerous, but Limsa's more...seemingly dangerous.

See, in Limsa, you mess with someone, they'll just kick the shit out of you and be on their merry way. In Ul'dah? It's a blessing if they just leave it at stabbing you in the back.

The big difference is that Limsa looks more dangerous on the surface, because it's a rowdy den of pirates, but it's actually not that bad -- Ul'dah, on the other hand, has a thin veneer of civility over everything that hides how dangerous it really is, and that's what makes it the more dangerous city.