My list ranked strongest to weakest.

Lan
Rand, obviously before he lost his hand
Riatin isn't that bad. He genuinely had Rand on the ropes and gave Lan a pretty good fight.
Galad
Valda, his loss was the result of arrogance and that's a fatal mistake that he probably only made because of who he was fighting.
Gawyn, for some odd reason I feel like this guy has managed to survive mainly on luck and his youth. I don't think his youth and luck would let him stand a change against any of the people higher on this list.
Gareth Bryne, the warders bond put him above Rodel and Tam. If he didn't have that, I'd say it would be a toss up between those three.
Rodel, we haven't seen much of him, but he does seem pretty awesome. In his youth, he probably would've goten a higher rating.
Tam, he is mainly ranked so low because of his age and lack of practice for so many years
Sleete,
Turak,