Your title and your post ask very different questions.
Do I consider myself marriage material? Not much. I'm 49 years old and have never been married, so any woman who knows that much about me is going to see a big red flag waving over me. If I were divorced, with an ex-wife with whom I squabbled and a couple of kids who gave me terrible grief, I'm sure I would be a much more promising marital prospect.
What makes someone marriage material for me? Hard to say, since I've never met anyone who seemed like it to me. I imagine that the main things are (1) that we trust and respect each other and have a high regard for each other, (2) that we have common tastes and interests and get along well together, and (3) that we turn each other on sexually -- and probably in about that order of priority, though I consider all three requirements to be non-negotiable. I've never had a relationship that fully met more than two of those conditions.