The admirals are all pretty much the same fighter. What's the point of arguing who's stronger? We're not at the point of the story yet where that sort of thing makes a difference.
Any difference of strength between the three won't be an issue until their personalities are fleshed out more and when and if their abilities become more fleshed out. Right now, they're all pretty much invincible guys meant to beat down the lesser pirates,that's really the only thing they bring to the table right now.
@LightningAce:
I don't think we'll ever know who is. I'd probably go ahead and say Kizaru, simply because he is the only intangible Logia, and unless the other 2 can use Haki, there is no way they'd ever be able to physically hit him, assumin they could because of his speed.
Considering Rayleigh could keep up with Kizaru pretty well, I think it's smart to throw the whole "lightspeed means he's faster then everyone else" idea out the window. Abilities don't really mean anything with these guys, the shichibukai and the admirals, they're all pretty much the strongest guys out there. They'll match each other for no good reason, just because they're that good.
Look at Moria, he's been nearly untouchable to all but Jimbei with shadow enhanced strength and some swordplay. All the hypothetical abilities his shadow powers can do haven't come into play, and frankly with the way this war has been going it wouldn't make a difference.