It's really just been the DATDA class with inadequate teachers, well that and Divination. Snape, McGonagal, Flitwick and Sprout are all presented as very accomplished wizards in their fields, and other than Snape needing to refine his teaching technique a bit, they're all presented as good teachers. Hagrid might not be a great teacher, but he knows his stuff.
DD even though he isn't a professor anymore...well he's a genius and I assume he was good at teaching students.
McGonagall is highly regarded.
Snape is the professor we see most of next. He's highly regarded as a potions master and DADA.
Flitwick is supposed to be good.
Slughorn could hold his own.
I think there is one thing to note that the whole of magical education is poor when compared to our own education system. However Snape's actions towards Harry in particular are shown in what some call the best chapter of the series in book 7.
And yes, Lupin was the best in the book and in the movie with how he worked with Harry. And it's then shown in the book when Harry starts teaching everyone DADA.
That's all true, we don't see McGonagall teaching much and Sprout seems very competent. I am trying to relate the teaching of wizardry to something like post-secondary school in our world and it just seems like it doesn't match up.
The real disconnect for me comes from seeing how keen Harry is at potions using Snapes book, and then remember how awful Snape was at teaching (apparently). Since we mostly see Snape teaching I probably just associated his style with everyone else's style.
Also I'm probably thinking about it too much.