With those gone, there isn't anything particularly compelling about the current ThinkPads. In that case, just pick most anything and go with it. Ubuntu should run great on most anything these days.
https://wiki.ubuntu.com/Testing/Laptop
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And a bunch of earlier HN discussions:
https://news.ycombinator.com/item?id=6514512
https://news.ycombinator.com/item?id=5088260
https://news.ycombinator.com/item?id=5503047
There are choices - Fedora, Ubuntu, Mint, OpenSuse etc. and each distribution differs in user interface and the hardware support (graphic cards/wifi/bluetooth etc.). So far, Ubuntu seems to have a slight upper hand on hardware compatibility.
You can still run into issues if the model of laptop is brand new. Things like graphics and wifi maybe a little iffy.
It's the same story with distributions. So often, someone asks what the best one is, and several people say something like "They're all good---you can't go wrong!". Which, again, doesn't agree with my experience. There's always something janky no matter what distro you choose. But the good ones (like Ubuntu pre-Unity) had considerably less jankiness.
I wish we lived in a world where you could install any Linux distro on any random hardware and have everything just work. But that is not the world we currently live in.
The only issue I had with my Toshiba Satellite P855-S5312 was getting around secure boot, which is easier now. I've been running Ubuntu on it for about 15 months with no issues.
Best is vague. Best bang for your buck? Best ultra portable? Best workstation? Best battery life?
If you want something small and portable my Asus X202E works well.