I like Debian's measured pragmatism with ideology, how it's a distro of free software by default but it also makes it easy to install non-free software or firmware blobs. I like Debian's package guidelines, I like dpkg, I like the Debian documentation even if Arch remains the best on that front. I like the stable/testing package streams, which make it easy to choose old but rock-stable vs just a bit old and almost as stable.
And one of the best parts is, I've never had a Debian system break without it being my fault in some way. Every case I've had of Debian being outright unbootable or having other serious problems, it's been due to me trying to add things from third-party repositories, or messing up the configuration or something else, but not a fault of the Debian system itself.