OK, OP. I want to be clear before I answer this: this is about sexual attraction only. These things alone are in no way sufficient to make me want a relationship - even a friendship, actually.
And it's a simple answer, too. To make me want to have sex with a dude, a dude has to be what I find sexy. And the more boxes he ticks the more likely I am to want the sex. This is basically my FWB from last year. Physically/sexually he was my ideal, and it's pretty rare for me to meet men like that (as I imagine it is for all of us, when we compare real humans to the specifics of the 'ideal man/woman' in our heads). He was naturally built (by which I mean natural masculine/broad build, he wasn't much of a gym-goer or even an exerciser in general) in the exact way I like men built (breadth + depth), blue eyes, perfect hands, facial proportions (square headed/wide-faced), shoulders, chest, dick (oh god), even his fucking FEET were sexy to me. Also, his manner. Unlike a lot of men who I see attempting to come off as more commanding or domineering than they naturally are - he tried to come off as more of a nice guy than he actually was. And he wasn't a nice guy. Not in the straight meaning of that phrase, not in the 'nice guy' TM meaning of that phrase. He was kind of a caveman, actually. I really didn't like him as a person very much. Didn't hate him, but certainly wouldn't have wanted anything to do with him if he hadn't magically been everything I fancy in male humans. He was unreconstructed, sexually. Unaffected in any way beyond the totally superficial by what certain sectors of society tell men they should be. Sure, he knew what he was supposed to say and he knew enough to realize it wasn't cool to talk about women in certain ways, but none of that successfully hid who he fundamentally was, IYKWIM. At a certain point, niceties went out the window with him.
I'm aware as i write this that I'm probably going to get loads of red pills on my ass (or blue pills saying the opposite) saying "ha ha! yes! this is everything we said! you have proven Rp, you dumb AWALT hooooo-er!" And I mean OK, fine. But I would like to emphasize that this was a very specific situation with two very specific people. And no part of me thinks all women would be into this guy (quite the opposite, actually).
BUT. That said. I fucking loved it. It's hard to explain this. The relief of being forced to let go when one is a fairly anxious/self-conscious person in general life. I'm always overthinking everything, worrying about everything, I'm one of those type-A dickheads. This guy could turn off my brain. The not-liking his personality/character part actually made the whole thing easier and simpler. I knew how far to push him. And pushed beyond a certain point, like I said, caveman. He didn't allow me to choose. He didn't give me the psychological room to think or consider. It wasn't about me at all. It was about him and what he wanted/needed. It didn't matter what I said or believed or that I was smarter than him or more educated than him etc. Only the sexual connection mattered, and he was the total boss of me in that realm. Not because either of us CHOSE that, but because it was an obvious fact. Nature had decreed it. Ha.
I'm aware that this makes me sound like a bit of a nutjob btw. I'm actually trying to answer the question honestly.
I've never had a relationship so singular as that one and I'm not sure I expect or want another one (the sex was perfect, the rest of it was tedious). Nor am I sure that this is something a lot of women would be interested in. Maybe they would, I dunno. All I know is he made me do what he wanted me to do. He made me want that. Nothing about him left any of it up to me. And it was one of the best things ever.