Windsor and Newton Series 7s were my first expensive brushes. I'm rocking Raphael 8404s right now though and I've been a lot happier.
I'd say that the Harder Steinbeck Infinity series are probably the "you've made it" of mini painting with lots of little tweaks and QoL features, but my Iwata Eclipse has been a perfect work horse for me and may be a "pinnacle" for mini painting as far as overall value.
Not sure you've made it over there yet, but feel free to join us on https://kbin.social/m/minipainting. Always love to see more work over there!