In just a regular one on one fight, he probably loses to chuunins. Easily beatable by any jounin like Darui, Kitsuchi, Kakashi, Gai, Temari, Kankuro, etc.
As a squad captain, he is probably around mid jounin - high jounin level. But he is only as good as his teammates and how familiar he is with them. He is very situational. With preparation like we saw him have against Hidan/Kakuzu he is an extreme force and can fight at a high jounin/low kage level. He was as valuable as Kakashi, if not moreso, during the initial fight before Team 7 came.
Overall having him as a tactical battlemaster in charge of a large military force? Probably kage level.