they were about 20 years judging from ages of charachters in databook 4 and that was 3 vs 1 not 1 vs 1.
Back than Jiraiya literally couldn´t believe than someone (nagato) could beat Hanzo single-handedly. So he actually admitted inferiority to Hanzo. Now its generally accepted that without Edo Orochimaru is inferior to SM Jiraiya. You also have Danzo here.
Actually, Zetsu Orochimaru, with Zetsu Level Mokuton, Spores, and a durable body that can make Perfect Clones (not sure if Oro has the last one) is generally accepted to be a tier above the other Sannin, while his prerevival form is acceptable as a deadlock, with Hydra and Edo restricted.
However, Neither of these Shinobi can handle Bringer of Darkness, while Manda can, and at this point, Hashirama can use Yamato level Mokuton, and So,the Kages can easily hand to hand Danzo until his Izanagi runs out, and Hanzo will easily be outmatched by Orochimaru, while the Giant Snakes take care of the other summons.
Orochimaru after getting his hands back is >> Hanzo. An Orochimaru who could use jutsu toyed with Four Tailed Naruto.
There are also arguments for the Anzos.
