Is Firefox still a good (enough) browser for privacy?

I would say so, it's definitely my browser of choice. I'd add uBlock Origin and Privacy Badger as add-ons, as well as enable them to work in private mode. This is a reasonable enough solution for myself and most folks in my opinion (my background is software/network security.)

A good one-stop-shop site for privacy information that I recommend to folks is privacytools.io, however some solutions proposed there may be tedious and a bit overkill for your specific threat model.

In a world dominated by Chrome and Chrome derivatives, Firefox stands as the lone guard against full monopolization of the browser market.

Since other browsers are even more heavily dependent on Google, one of the least privacy concious companies, Firefox is better by default.

Because unless people are willing to hard-fork Chromium in order to stop Google's slow transition away from end-user empowerment, using Chromium will strengthen Google's power.

Firefox isn't particularly any better or any worse than its competitors in most departments. Comprehensive extension options always outweigh browser-specific features or capabilities, and there's a thriving ecosystem around both major players. Telemetry is perhaps the biggest differentiator, and what you see groups on reddit dot com and twitter dot com regularly flip out over - in this regard, Firefox is clearly the better option, collecting much less data than Chromium by default and providing user-facing options to opt out of all data collection.

You also hear much more about the flaws of Mozilla and Firefox because they're always held (perhaps unfairly) to a much higher standard than Google. The first Reddit link is a good example of telemetry-related FUD that seems to circle around, and although the Neocities article has some true points, it does mix them in with fiery rhetoric and certain controversial design decisions in an attempt to make Firefox look unfairly bad.

The Wikipedia article linked is also misleading. Chromium, the FOSS backbone of Chrome, has perhaps a larger user base than Firefox, but isn't mentioned at all / distinguished from Google Chrome.

It depends what you mean by privacy.

For me, when I think of online privacy, I think of online services only collecting the info that is relevant to their service and nothing more. For example, Google collecting information about what searches I perform as I type my queries into Google I can understand. Having Google track my online behaviour with Google Analytics, AMP, and whatnot is what I call overreaching, overbearing, and an invasion of my privacy.

In this case, I've found that Firefox with uBlock Origin does a decent job at stopping a good deal of that privacy invasion. Out of the box, it blocks a lot of Javascript and web browser defaults (like preloading) and you can configure it to go even further. Hell, you can flat out tell it to disable JS, images, fonts, all sorts on websites without any additional extra plugins. Not only that, but Firefox isn't in the data broker business and have built their brand on privacy first, so it would be foolish of them to start being invasive with my data as I go about the internet. I cannot say the same with Google Chrome or even Microsoft's Edge browser (as good as it is). Brave browser is made by an ad company, so no doubt they don't really care that much about privacy - at least not as much as Mozilla.

However, there's that other kind of privacy that other people online talk about. Not being tracked whatsoever, not leaving a trail, etc. To me at least, that's just a laughable idea - the fact that I went online and typed "www.tildes.net" meant that connections to a good few servers had to happen for the browser to even understand where that points to (DNS) and then going to Tildes, which exposes my IP address (and my IP address pretty much exposes the town where I live). Online smartypants might go "well just unplug and replug in your modem lololol" but the problem with that is that my ISP already knows I've visited Tildes and very likely keeps record logs of which customer with which IP went to whatever website. Use a VPN? All I've done is offloaded that information from my ISP to a private company. And to me, the privacy subreddit has this sort of tinfoil-hat conspiracy like thinking which is pretty dangerous if unchecked.

Now true, Mozilla does have things like Google search as default and it will send websites to Google's Safe Browsing service. Some people will see that as a "betrayal" of Mozilla. But if you realise Mozilla has to cater to the general public as well as techies, then having that service set as on as default while allowing it to be turned off in the about:config is a good compromise - their users are less likely to get phished when they go to www.paypal.com-realwebsite.org or whatever, and techies who know better can turn that off. The only other browser that I know that is equal or better than Firefox is Safari, but for me it has too many compromises to be of use (mac only, and extensions are a nightmare).

Turns out the above isn't even true thanks to @dblohm7's linked article. Only the download gets sent to Google, and only in very specific examples (i.e. when all possible options have been exhausted). The article goes to show how much Firefox takes privacy into consideration, so I'd say read that, as that should tell you how much Mozilla takes privacy seriously.

It's all about moderation and being sensible, really. Nothing you do online is untracable, but you can do your best to avoid being tracked and traced by private data broker companies who just want to pilfer through your data to make $$$ of you.