I like Inoreader[0]. The web app is plenty snappy for me, and supports basic vim nav keys, which is a lovely plus. The free plan's 150 feeds are sufficient for my use case. The mobile app also performs well. Mostly it just gets out of my way, which is all I really want.
100% this. Inoreader is the aggregator I wanted to make for myself, but never did. It's got all the features I ever wanted. Been a paying customer for years now. They can be a bit slow on fixing bugs or cleaning things up (duplicates in search results, for example), but I love that it lets you enter your own CSS fixes. In general, it's a great example of a boutique web service that we all should admire and support.
And Tridactyl as well for Firefox, not to mention qutebrowser, from which I write this very reply.
The annoying thing with such solutions for webapps is when there is a more fluent implementation of navigation in the context of the application. With j/k bound to normal scrolling, I then have to resort to link-hinting to navigate among articles in the feed. With app-native navigation, these can jump among articles.
A good vim-binding experience is not just j/k for scrolling up and down (:
[0] https://www.inoreader.com