I use Debian as an operating system because it is extremely stable, and I do some homeserver things on it. It also has t customisability that I like without been extremely convoluted (like Gentoo) or too terminal-centric (like Arch). Also its nice to just be able to download the .deb file off of a website if they aren't on FlatHub
I use android as my phone operating system of choice because I can't be bothered to install something like PostMarketOS or LineageOS.
I use LM Studio for my self-hosted LLM's, because it has a really convinient GUI, and quite a few andvanced features, such as compatibility with search engines (such as SearXNG).
The official LM Studio website
Waydroid allows me to seamlessly run android apps on my Linux machine which allows me to use apps that dont work natively on linux (or any distro that isn't android based, but I don't count them as linux). It can also be very useful for apps that are usually only for mobile devices (such as Steam Guard Mobile Authenticator).
Firefox is definitely the best browser. It is open source and not a chromium fork!! It also has solid privacy settings, even if they are bad by default.
Thunderbird is just a good email client.