Last great sitcom?

Seinfeld

Big Bang Theory --The first 5 season are very strong with few bad episodes.

I interpreted your question to mean in more recent times of a show that has ended...but then you said no wrong answers which explains why people are answering "Seinfeld," for example.

There's a lot of good ones in decades past but I'm gonna mention the first one that came to mind, which is The Middle. It is the most recent of sitcoms that ended that I really liked.
I still miss that show but there wasn't much more they could do with it. I'd rather a show go out strong than die a slow death.
The Middle did have a few stinkers at times but over all, it was a great show.

Since the ending of The Middle, I haven't seen any sitcom that has even sparked any interest for me according to the previews they show.

Seinfeld!