You have to be the one that decides what's most important to you because that could be different than what someone else wants, but I think it would be a good idea to look for someone that

- you can communicate well with (meaning he both listens to you and talks to you)

- respects you

- is responsible

- is willing to compromise (which doesn't mean always doing exactly what you want, but does mean not always insisting in exactly what he wants)

- is both willing and able to satisfy whatever your top two love languages are.

With that core set of qualities, and assuming you do the same for him, I think your odds of success are pretty good. There might be other specific things that are important to you though that you would also want to look for.