Yes, I recently transitioned to net core. First of I'd say that trying to find a 1:1 feature/convention parity between the frameworks won't work. E.g. in aspnetcore you'll add an attribute to model and after generating a new migration the column change will already be in-place. Most of the time it works out-of-the-box, you can always edit the migration if needed
What I found lacking (at the time) was specifically a better Webpack integration, similar to rails.
Also I got used to having rspec, in net core world you have xUnit which is something like ruby TestUnit.
At the start I also found DependencyInjection a bit confusing and also the fact that in Aspnetcore the models/entities aren't like AR models where you have a bunch of validation/instance methods inside it. In .net you try to separate everything in repositories/validators/viewModels.
But yes, unlike Rails, .net won't have an opinionated way on how to do things.
All-in-all I'm quite satisfied with the experience. Though I will say that Rails is still a tad more "batteries included" type of thing.