Guess I'm the lone dissenter. I don't have experience with the Yaesu 350 because it was already out of production when I started looking, but it was what I started looking for. I ended up buying the 400 and I've been perfectly happy with it. Menu navigation isn't bad once you get used to it but I'll admit it seems a bit clunky.
I've not used the Kenwoods but I do know they have a solid rep in the APRS line up so you'd be hard pressed to go wrong there, but I've been a pretty solid Yaesu or Icom fan-boy, though the 400 is my first Yaesu mobile. I usually run along the lines of Yaesu HTs and Icom mobiles, but this Yaesu won out for its APRS mobile. It's been awhile now so I don't remember details but for whatever reason I had at the time the Kenwoods just didn't do it for me.