I think that, in the moment, when the two people are with each other, talking about how they love each other, the foreplay, and when they are having sex, etc., women easily take the cake in having the higher capacity to love. Women are just more expressive and let you fucking know how they feel - besides, almost everything women do in the bedroom you already know is going to be sensual as all hell, it just comes fucking natural to them...
As far as I'm concerned, though, the flip side is that I do think men are historically much, much, much better at detailing their love for a woman (or man too, but historically, it's almost always women) in artistic form, in various mediums - poetry (think Shakespeare, Rumi, Lord Byron, etc.), oil paintings or sculptures, music (Beethoven and his 'Moonlight Sonata' that he wrote for his furtive girlfriend), etc. And yeah, I know this argument is clearly greatly complicated by how men were the only gender who could really express themselves in this way for thousands of years per societal norms, but, actually, I'd still stick by this argument even in the modern day. Men are just fantastic at retroactively looking at their love interest and putting them up on an artistic pedestal. It's somewhat ironic since this would seem to be the much more feminine thing to do, trying to capture your sexual fantasies or real moments in fancy ways.
You can say I'm totally, wrong, it's cool, but think about it, yo...