Assuming that Jaime was talking about swordsmanship and not including other forms of combat, then I'd imagine he'd be talking about Barristan and the Cleganes. Oberyn seems to specialise in other weapons, and Loras is foremost a jouster. I don't expect he even knows who Bronn is (although I don't think Bronn is quite as good as some fans would suggest anyway) and the qualities of Garlan Tyrell seem relatively obscure even in-world.
Or, you know, Darkstar.







