Linux

I use it since I know computers and it's better for Adblockimg than Chromium based browsers nowdays.

Because it's NOT Google and Firefox not embracing WebBundles or the “Web Integrity API” standard from Google. Google want to INTRODUCE DRM on the web.
And just recently YouTube (==Google) now also have very strict medical policy, so it can only follow the WHO guidelines. Google is evil, look out. Even Dr. Eric Berg is getting censored. Look out people.

I really like the developer tools. I always the install the developer edition (which is basically just the beta) and I find the defaults and menus more intuitive than Chrome’s, though at this point, they’re probably at feature parity. I could probably get Chrome to work how I want by changing settings but why? It’s not faster or better at this point.

I have ideological reasons too but honestly, the main reason is just that I like Firefox better. As a developer, it’s also nice to have Chromium (or Google Chrome) completely clean. If there’s a bug I can’t recreate in Firefox, I can open Chrome with no extensions or cache. Since that’s sort of the “default” for most users, it’s nice to keep my daily driver separate.

For me, it's not as memory efficient as something like Edge, but it handles having a lot of tabs open much better. It also has a lot of powerful features under the hood, and some really good power user addons, like Tab Groups.

I have been using Firefox since I can remember. That it is open source is a huge plus. The features it offers are great.

Originally I started to use it because I'd heard there was a new update to its rendering engine that made it feel faster/better than chrome. After testing it out I did think it felt better at the very least. Now I'm using it mostly for the same reasons and to reduce my dependence on Google/Chrome.

Many reasons. Many of which is down to how Google as a company is reaching between the proverbial couch cushions to get at the loose change to make a profit. Default opt-in tracking, breaking ad-blockers, and probably more which I forgot about since I abandoned Chrome years ago.

Chrome on android becomes unbearable with ads, and full screen vid ads when i just want to read the news. Use ff for the addon.

I only use it so that I can watch DRM content (Udemy, HBO, etc)

It came preinstalled.

More open and honest and fight for privacy. Also their devtools are top notch.

Because Chromium and its derivatives suck. Is it really too much to ask for a traditional menu bar rather than a stupid hamburger menu?

Not my main but Firefox containers are damn handy.

I've been using Firefox since 2002 when it first became available, at that point it was called Mozilla. It's definitely the browser that I've used the most in about 25 years of browsing the Internet from home. Firefox has a great native Linux version and seems to be widely promoted by most distros. Since switching to Linux seven years ago I also started using Chromium (not to be confused with Chrome) and Opera, both of which also have great native Linux versions.

I was shown it by a mate, along with soulseek, in like, 2006 or so when in sixth form. It was way better than what I was using at the time (IE)

At least that's what I remember, pretty sure that was the date. I remember soulseek was before by a bit actually as we used it for trading At the Drive In and Mars Volta tracks

I've carried on using it because of plugins, adblocks, privacy, etc.

Are they the most privacy respecting? no.

are they privacy respecting ENOUGH? sure

Privacy, real ad-blocking, and fighting for the open web. Also, actually being free software.

For add-ons, mostly. I use Tree-Style Tabs and can't live without it at this point.

It doesn't suck and just works. Really well customizable and adblocking/ security is better than what chrome has turned into. Chrome used to be decent but is garbage now. I'd rather use edge before chrome.

Firefox supports a font technology for less common scripts, Graphite, that the for-profit-corporate browsers do not. I use one of those scripts once in a great while. So I'm locked in until OpenType has better support.

I can't find any reason to use an alternative browser

Honestly, when I got my first Ubuntu install disk and got everything up and running, it was the default browser. I just never looked back.