I did use Roslynator. It helps with clunkiness of VS and gives you some refactorings but it felt far from Rider. Roslynator also doesn't fix abysmal code autocompletion. Even after the 'AI autocompletion' that VS introduced like 2-3 years ago, it was always just bad, classes you actually want to use are so far down I found myself typing whole class names by hand anyway.
Almost always when somebody shits on Visual Studio s/he either uses C++
(and there's significant difference apparently between C++ and C#) or used it with Resharper, or without any extension/addon at all.
Just try Roslynator if you haven't used it yet.