I’ve had good luck with an X201, W520, and T480 - all thinkpads. Haven’t tried any of the lower end lenovo models. I got my W520 new and my other ones off craigslist.

If you’re looking to get a preinstalled OS and from a refurb vendor, an interesting option would be buying from libreboot. Debian/KDE by default or you can choose your own distro. Libreboot is a good cause, and sales funds the project. You’ll have the most secure bios on the block.

I switched to nixos years ago. Its better now than it ever has been as far as available packages and etc. But it does present issues if you get off the beaten path - the “now you have two problems” issue. For instance:

• if software is not packaged for nixos already, you won’t be able to follow the ‘build from source’ directions on its github page or etc. You have to make a nix package or at least development environment first. That can be tricky and you won’t have help from the software dev.
• If software downloads exes that require libraries to be in a certain standard location, well, they won’t work. Android studio for instance, downloads compilers and so forth. There are workarounds, mostly, but it can take a while to discover and get working and I’m sure many people give up. Again, the android studio software and documentation will be no help at all.

That said, more and more projects are supporting nix, and nixpkgs has gotten really big. I think they support more packages than any other distro now.