I think the name you ended up with is the best. It has a nice flow, it's pretty, and doesn't feel too worn.
I find
Katherine Elizabeth to be too worn for my taste.
I love
Alison but agree that it doesn't flow well with
Katherine.
I like
Katherine Elisa, too, but I don't think it flows as well as
Katherine Marie.
Katherine Elise would've been nice, though.