Brave is great for less techy people because it’s defaults are good enough. It’s not necessary to tweak settings and install add-ons to get basic privacy. I definitely prefer Firefox, but it takes some knowledge to get it to surpass Brave’s defaults.
I’ve been using Runbox for a couple of years and agree the web interface is lacking. There were also multiple significant server outages last year, but it has been much more reliable this year. As long as you don’t use the webmail often, Runbox is a good affordable email provider and is great for families due to the low cost of sub accounts (additional users).