My Firefox addons as of Firefox 104 (they haven't changed in a while)
I last wrote about what Firefox addons I used back in the era of Firefox 86, about a year and a half ago. I haven't written about this since then not because I don't care (addons are actually central to my Firefox experience), but because my sets of addons basically hasn't changed since then. There are multiple reasons for this; I try to be conservative about adding addons (partly because of past bad experiences with instability and memory leaks), my needs and interests haven't changed very much, and my current set of addons has been trouble free as far as I can see.
The short list is that I (still) use Foxy Gestures, uBlock Origin, uMatrix (which is still not quite dead), Cookie AutoDelete, Stylus, Textern, Cookie Quick Manager, Certainly Something, HTTP/2 Indicator, ClearURLs, and Open in Browser, although I'm not sure that's doing anything for me. I'm still using HTTPS Everywhere in some of my browser instances, although I've started to turn it off since the EFF is deprecating it. These addons are all stable enough that I can have Firefox running for days at a time without visible memory leaks or performance issues.
(On the other hand, it's been a long time since I looked at how much memory my Firefox instances are using, and now that I do it's not really a small amount of virtual memory. However, the resident set size is under 1 GB. Since I'm not feeling any sluggishness in performance, I'm probably going to let this sleeping dog lie.)
In the past, I've used Decentraleyes in some browser profiles. Based on things I've read about it being outdated and not so useful, I've increasingly wound up turning it off. I've also experimented with Right-Click Borescope (Github) as one way to be able to see bigger versions of images. I'd like to find a good extension that just enlarges an image for me (or all images on the page), but everything I've tried so far has had various bad effects. It annoys me that the best way to do this is to have 'zoom text only' turned off in Firefox's settings and then zoom the page, but such is life.
Sometimes I wonder if I'm missing out on things by not seeking out more addons. On the other hand, I suspect that I'm using more addons than average, and there are things to be wary of in using addons (and using lots of them).