In terms of pure feats, I'd say:
1. Itachi (His Amaterasu feat was so good that the jutsu was straight-up retconned.)
2. Orochimaru (controlled weakened Edo Hokage, Manda, etc. Pretty boss.)
3. Jiraiya (Gambabuta, Yomi Numa, etc. Boss, but still clearly weaker than Orochimaru in feats back then.)
4. Gaara (His ninjutsu against Kimimaro was monstrous and he could transform into Shukaku.)
5. Kimimaro (He had superior skill/regeneration to rusty-Tsunade, plus he was a logia with beastly ninjutsu.)
6. Tsunade (She was really rusty back then, but she still had Katsuya, super-strength, etc.)
7. Naruto (KN1 speed and power, regeneration, and most importantly: Gambabuta.
8. Hiruzen (He was still skilled enough with tags and Enma to beat down pretty much everybody in his vllage.)
9. Kakashi (He had a huge stamina problem with his Sharingan, but he was Hokage-level in skill, though not power.)
10. Kabuto (He was hyped to be Kakashi's equal, and while very skilled, his feats weren't quite at Kakashi's level IMO.)
A. Gai was basically just Base Gai back then. Tough, but definitely not unbeatable.
B. Kisame was strong, but ultimately he only showed strength, limited absorbtion, and normal-size Suitons back then.
C. Asuma was prety deadly and skilled, but his Hien was much shorter back then and thus a bit less useful.
D. Kidōmaru, in terms of FEATS, was a beast: armor, webs, sniping, kuchiyose, sage/curse energy, etc.)