I think Racicale, Baikal, SabreDAV or NextCloud are the most common choices. But I believe only one of those isn't written in PHP.

I'd really recommend digging into the "hacking" though. Unless you lean from your specific mistakes and avoid that in the future, you might face the same issue again. And I mean it could be a security flaw in the program code of the WebDAV server. But it could as well be a few dozen other reasons why your server wasn't secure...