The Eleven

The Eleven is pansexual. In terms of aesthetics, he's fairly conventional in what he finds attractive. In terms of who he tends to be really drawn towards, the answer is freaks. In canon, his wife is a mutant whose face was destroyed by chemicals. He has a weird thing going on with a sadistic android made out of spun sugar. He perceives himself to be a freak and he likes other freaks. He has a fairly low libido and at any given point is probably not thinking about sex. Also sex is often awkward because he has ten other personalities inside his head and all of them have different preferences and opinions, and are likely to make mood-killing comments. So most of the time he finds it easier to just...not. But when he is turned on, he rarely does anything in half measures. He'd rather Dom than sub, and would rather top than bottom, but he's not averse to switching. What I'm saying is that his ex-wife probably pegged him at some point.

Although the Eleven appears human superficially, he is not human and his biology is not human. Canon mostly emphasizes internal/invisible differences, like having two hearts. So this is my headcanon (partially extrapolated from weird canon details) for xeno sexytimes.
1) There is obscure canon that states that Gallifreyans have a sensitive nerve cluster by their left shoulder/collarbone. I headcanon that "sensitive" also means erotically sensitive and that he can orgasm multiple times through the right stimulation of this area. The quality of the orgasm is slightly different (does not involve ejaculation) and is tied to telepathic instincts and hormonal triggers. The original biological purpose was mate bonding and triggering physiological changes beneficial to reproduction, but Gallifreyans have been so genetically bioengineered at this point that the original biological purposes of this nerve cluster are pretty irrelevant. But if you want to turn him on, this is the button.
2) There is also obscure canon than Gallifreyan internal body temperature is significantly lower than human. So I headcanon that testes are not much (if at all) descended, because there's no biological need for it on account of not requiring the temperature regulation/cooling that humans do.
3) There is obscure canon that Gallifreyans are evolutionarily descended from some kind of alien canid animal. So I headcanon that there's no foreskin, but there is a bit of skin at the base that's a vestigial penile sheath. And the overall shape is slightly different, mostly in that there's not a pronounced head. Aside from that, erection functions basically the same as in humans.
4) Gallifreyans are telepathic. He can use superficial telepathy in various kinky ways. (Sensation sharing. Psychic bondage.) I headcanon that deep telepathic connections are considered more intimate than sex. 📝