From best to worst, I would say

Lupin-He knew the subject well, and knew how to teach and connect to students

Crouch-He knew the subject well, and knew how to teach and connect to students, but he was also evil

Snape-He knew the subject well, but did not have enough patience to be an effective teacher

Quirrell-From what we’ve seen, he was a perfectly competent but unmemorable teacher. Also, he was evil.

Lockhart-He was good at connecting with students, but he was an idiot who knew nothing about his subject.

Umbridge- She was a sadist who was actively trying not to teach.

Carrow- He was a sadist who was actively teaching the opposite of what he was supposed to.

Well, since Barty Crouch jr. and Snape are the only one who actually taught defense against the dark arts (all the others just did dangerous creatures) I would say I’m tied between them. Also the worst teacher would have to be Lupin because he wasn’t there for a lot of the lessons (of course this is from an acedemic standpoint.) I guess Umbridge did teach DADA but not in a practical way. If you want personal preference the best would be the Carrows (I wanna use dark magic 😕) and the worst would be Quirrell (who wants voldermort on the back of their teacher’s head?)