Snape was probably bad at being nice because he had a horrible backstory-I honestly can't blame him-in my opinion, at least-

Umbridge, of course! Quirrell is a close second.

Just kidding. Lupin, of course! Fake Moody was good as well despite being a death eater.

Professor lupin

Lupin

Snape was a good hero at the end but he wasn't a good teacher

In my opinion, Lupin is the best

Lupin obviously

100% Remus

Barty

Lupin of course!

Remus Lupin of course