Django is my number one, but I think certain languages and the communities behind them - including Go and Rust, for sure, fit much different use-cases than Python/Django and thus there's good reason why you don't find massively popular full-featured web frameworks [for those langs].
Node.JS, on one-hand seems to take the approach of Go-lang - standard libraries that do basic web-handling well, but on the other hand, I think it is tarnished by Javascript's reputation for having too many third-party packages, too many options, new framework every week, etc.
C# / .NET core seems to be a strong up-and-comer alternative for teams looking for a full-featured and well-supported application framework with more type safety and performance than Python/Django or RoR. Elixir / Phoenix, as well, but that caters to an entirely different crowd.
I expect most Go users are not using much in the way of frameworks.