With there being a whole lot of them who aren't all that well known, maybe I'm missing someone here; but I can't say I find any of them the least bit appealing or "sexy". Eew!! It's a big deal if any of them even look at all "presidential" - let alone, "sexy". LOL
Others have said "Adams":
I'll give Adams a few points for some thoughtful letters (or at least letters that created the impression he was being thoughtful; he was, after all a lawyer but also someone aware of having a legacy), but he (and eventually his wife) just picked up and left the country so they could go live in Europe. Major points off for anyone who leaves his kids for years on end. Within the context of role in America's history, no doubt he deserves a lot of credit and respect. Still - come on - the man wasn't an appealing/sexy looking man.
How about Millard Fillmore - with his little "wingy-doo" hair-do? Maybe that was considered sexy in those days?? (Millard Fillmore has kind of a little bit of an Alek Baldwin thing going on there, do you think?) (Not saying he's sexy - just saying.. :) )