I like both a lot, but my vote goes to
Alice.
I think
Matilda is much more likely to become popular than
Alice.
Alice Juliet is very nice, though I think
Alice Matilda would be gorgeous.
I think
Ali could easily be avoided for
Alice. Harder for
Alexandra, but it shouldn't be a problem for
Alice.
Hildy is atrocious IMO, sorry. I prefer
Matilda with no nickname.