I am, obviously, a j/a shipper, and all my favorite shippy moments belong to them (and I've seen many of them mentioned by others here, too!).

The two moments that immediately leap out as bits I played over and over and over and wore out videotapes are two of the most obvious, I suppose. The first is the end of LATP3, not just the reactions to the kiss, but everything leading up to it. Aeryn is terrified of taking this emotional step. She's exercising, trying to work off her nervousness, and work up her nerve. And it's John, the one who TALKS about feelings, who's, well, trying to talk. And when he sees what she wants to do -- the compatibility test -- he goes completely quiet himself, as if any word or movement from him will cause her to lose her nerve and flee.... It just epitomizes their relationship at that point in time for me, Aeryn's fear, John's patience -- but both of them aware that this is a monumental step.
The second is at the end of of SoD, when Aeryn is standing, alone, contemplating her return from the dead, and John comes in to see her, the first time they've had to talk since he killed her. She can't deny that she loves him, he can't deny he loves her, and that kiss is just blazing hot! I love the way they continue to touch each other while Aeryn tries to explain about Zhaan, and why she can't allow them to act on their feelings. (Such mixed signals poor John is getting!) The sheer strength of their love, and how much they want each other, just blows me away!
(And if we want to get totally heartbreaking, I also adore TJohn's death, and the end of DWTB....)
aeryncrichton, Southern California