[csytan]

I've been using Python's Tornado (http://www.tornadoweb.org/) for years now.

Now on version 6, it's fast, well maintained, mature, and has good docs with readable code.

@bdarnell has done an excellent job maintaining it.

Here's one example:

Tornado supported async style coroutines before asyncio was a thing. Now it uses asyncio under the hood by default -- and it did so with an exceptionally smooth transition.

[thijsvandien]

Same here. In addition, it's incredibly versatile, has abstractions that I like, and ships with the right amount of stuff. Most importantly, it never gets in my way. I just keep coming back to it.