Intensity's a big one. Part of that is extremeness/depth of feeling. Hmmm, but the intensity would be diamond-like rather than fire-like. It's an introverted intensity... compressed.
...but the BIGGEST attraction is a guy who treats people well. Someone who respects human dignity, who's slow to judge/condemn, who holds people and knowledge in highest regard, who's always looking to grow and learn, who's humble, honest... ahhhh, I'm getting turned on you guys... not kidding...
*breathe*
OK, so an intense person with a soul that outshines the morning star. Second tier attractions include art appreciation/talent, patience, and cooking ability. Regarding that last one: I'm not picky, he can make mac&cheese all he wants, but nothing melts my heart like free food.
EDIT: Someone who accepts and appreciates ENFPs for who and what they are is HUGELY attractive.