I like both names, but I like
Veronica more. However...I would avoid
Veronica because of the possible nn
Ronnie. Even the possibility that my daughter could ever be called
Ronnie renders it unuseable for me, although I really like it. I believe that you shouldn't use a name if you absolutely hate a nickname for it, because the nickname may end up being used, even though you may not want it to be.
So, for that reason, my vote would go to
Clara.