I love my Pfaffs- I have 3. I've been using them since I was about 14, and not sure I could buy anything else! ;) Ok, maybe that's not true, but I do love them. They're straight forward to use, very consistent, and I don't have problems with them breaking down.
As for what other machines have a built in walking foot, I've not needed to research buying a new machine, so I can't answer that for you, sorry.