Unironically, sexual compatibility is really really high up.
If one of you doesn't like it, but the other does, then your relationship will never be really great for at least one of you.

The other thing is communication. If you can't properly communicate your wishes, issues and even just what you're actually doing, you will not have a healthy relationship.
This is also why avoidant people should never try to be in a relationship, they will only end up hurting the other person.