From my experience and point(s) of view, I don't even understand why the question needs to be put. I'm as puzzled as when a boss-to-be asked if I could imagine working in a project with a (even slightly younger, I think) female in charge. I answered that competence matters, not gender. Am I atypical? I hope not.
Among my very best friends today, I count my first fiancée (ca. 1962-67), my ex-wife (married 1970-1980), a woman to whom I recently intensely but in vain tried to sell the idea that marrying me would be mutually beneficial, and a much younger former university fellow student. Additionally, today, I had a 30 minutes amicable phone call from my latest (last?) fiancée. In all those cases, it's entirely and completely friendship only by now, to the degree than Plato in comparison would have been embarrassed by his lust. Also, I regard my three nieces (and their mothers, no surprise I hope) as near and dear friends.
I have male friends as well, but they (one case excepted) are not quite as dear to me as the female set mentioned. Among the men, however, is the current partner of my ex-wife. We meet quite often and the three of us always have a good and interesting time together. I'm also looking forward to seeing two more recently acquired partners of previous GF's.
I think that one factor that makes those friendships possible and working is what I've learned from Asian religions. In alphabetical order, I have absorbed influences from Buddhism, Daoism and Sikhism. I hope I was a reasonably kind and acceptable person when younger, but didn't really reflect on if and how my Christian environment affected me or on questions of morality etc.