Hmm hard to tell.. 4th was probably strong and all that but he dead now. dont know if he is the strongest there was or if he just was strong and really good with jutsus and smarts.. You dont have to be badass strong to be able to win and I dont think he "won" vs Kyubi by beeing stronger cause he aint. Thats what I think anyway. The 3rd is probably really strong aswell but he's getting old now and even if he's the Hokage he will be weaker than before but he might be good anyway .

Orochimaru is probably one of the strongest in the series, cause ppl like the 3rd wont go arround beeing alittle worried about him beeing arround for nothing, and he said maby not even I can stand up to Orochimaru now days, so I guess he's a really scary guy.

Jiraya dont know alot about what he can do nor what Hokage or Orochimaru can do but dont think Jiraya is the strongest tho.

Gaara well I belive he is insanly strong cause of the possesion but I think he is too unstable to be able to handle him self so he's not up there atm anyway. But would be cool if he where the bad ass

Naruto might become the strongest later on but he's faar from it atm..

Other's.. hmm only one I can think of is Itachi maby, one have to be pretty strong to be able to whipe out one of Konoha's strongest clans, but we dont know alot more atm about him so cant tell if he is insanly strong or not.

But for now I would go with Orochimaru at this point..