Hi Daniel,
Like you I'm also on the lookout for a replacement, especially for my dayjob as a developer. I need decent performance to run all the Docker containers with JVM processes, combined with the battery-life that can last me a large part of a day filled with meetings.
For personal usage my Librecore T400 should suffice for about 2 more years.
Lenovo is the brand I like, because of their build quality and their trackpoint. Going by the Arch wiki, running GNU/Linux on them should work if you settle for some binary blobs. Something like a T470p perhaps?
Dell is now selling multiple laptops with GNU/Linux preinstalled, although I'm not sure how many blobs they require. A friend of mine uses a recent XPS 13 and is very pleased with it, both the hardware and the distibution.
Tuxedo (linux-onlineshop.de), System76 and Entroware have recently come out with the 13" alu-cased laptop. Of these three vendors I get the sense that System76 is working upstream directly to get their hardware supported, and Entroware is doing so via the Ubuntu-Mate distro. I don't know much about the reputation of Tuxedo.
Purism has my preference at this moment, mostly because they have crippled the Intel ME for their models. The Librem 13 is similar to the models shipped by the vendors named in the above paragraph, but with a slightly different CPU. They seem to only laptop vendor taking part in the deblobbing proces. Their Librem 13 still contains some blobs, but they can do less harm. More on the deblobbing process can be found at: https://github.com/corna/me_cleaner/wiki/How-does-it-work%3F The Dutch Fellow Kevin (the_unconventional@) has more detailed knowledge on the state of blobs.
I hope others can chip in on this topic, so that I too can make a more educated decision in the near future.
Kind regards, Nico