It’s been too long since I’ve combed through FF’s Privacy and Security preferences. There were a few other options that I haven’t seen since I last looked. Thanks for the HTTPS-Only tip. I’ve been wishing for that for a long time.
Alternative in Chromium-based browsers is to use HTTPS Everywhere with EASE enabled. Should give a similar experience of “upgrade to HTTPS or block”.
That was possible in Firefox too, the nice thing here is the native support now.
I much prefer native support, and I avoid plugins unless absolutely necessary. 1Password is the only plugin I use.