Been running Linux on laptops for years (over a decade). Everything from XPS to Thinkpad and System76.
My first recommendation is to check the Linux distro wiki and see what hardware is officially supported. Ubuntu, RHEL / Fedora, and the major distros have lists and tell you what is officially supported; even sometimes down the the piece of hardware (i.e. Thinkpad fingerprint reader) and precise serial numbers. If you're not going to look at the distros wiki or you're not sure what distro you're going to run, the general rule of thumb is the older the hardware the better chance it is of being supported.
Now, my personal opinions:
I've owned two Thinkpads (x270 & x220), had a dell XPS 13 from work ~4 years ago, and my wife currently owns a System76 Lemur Pro (I have a Thelio Desktop). I've run Ubuntu and RHEL flavored distros on all these. Personally, the Thinkpads blow the Dells and System76 in terms of quality out of the water, and I'd argue they do with hardware support as well (if you're running RHEL / Fedora). The System76 works great with Ubuntu since the drivers and firmware are open (and POP!OS), but I'm not impressed with the quality of the product. Keyboard is low quality, as well as finish (footpads ungluing, finish on keys / track pad coming off, etc.). Dell makes a nice computer, but when I had my XPS 13 there were some major issues with HiDPI (I'm sure it's fixed now). I also didn't like the keyboard and the charging port was finicky.
Gonna be honest, you're going to get a downgrade. Not even just hardware, but software as well. Battery is much worse. Hibernate / suspend / lock is much worse. Linux (GNOME) is still a much better experience on a desktop workstation. Also, for what it's worth, I run RHEL 8 on my desktop workstation, and my next laptop will be a macbook air to pair with my iphone se (first gen!). Everyone's needs are different, but for mobile computing I'd rather have 15 hour battery life, software / hardware harmony, and be able to drive to an apple store for a replacement when my nephew spills apple juice on it when I'm out of town visiting family.
Another thing; supply chains are still really messed up. You're looking at 4+ months lead time for a custom Thinkpad right now. Just something to consider.
Been running Linux on laptops for years (over a decade). Everything from XPS to Thinkpad and System76.
My first recommendation is to check the Linux distro wiki and see what hardware is officially supported. Ubuntu, RHEL / Fedora, and the major distros have lists and tell you what is officially supported; even sometimes down the the piece of hardware (i.e. Thinkpad fingerprint reader) and precise serial numbers. If you're not going to look at the distros wiki or you're not sure what distro you're going to run, the general rule of thumb is the older the hardware the better chance it is of being supported.
Now, my personal opinions:
I've owned two Thinkpads (x270 & x220), had a dell XPS 13 from work ~4 years ago, and my wife currently owns a System76 Lemur Pro (I have a Thelio Desktop). I've run Ubuntu and RHEL flavored distros on all these. Personally, the Thinkpads blow the Dells and System76 in terms of quality out of the water, and I'd argue they do with hardware support as well (if you're running RHEL / Fedora). The System76 works great with Ubuntu since the drivers and firmware are open (and POP!OS), but I'm not impressed with the quality of the product. Keyboard is low quality, as well as finish (footpads ungluing, finish on keys / track pad coming off, etc.). Dell makes a nice computer, but when I had my XPS 13 there were some major issues with HiDPI (I'm sure it's fixed now). I also didn't like the keyboard and the charging port was finicky.
Gonna be honest, you're going to get a downgrade. Not even just hardware, but software as well. Battery is much worse. Hibernate / suspend / lock is much worse. Linux (GNOME) is still a much better experience on a desktop workstation. Also, for what it's worth, I run RHEL 8 on my desktop workstation, and my next laptop will be a macbook air to pair with my iphone se (first gen!). Everyone's needs are different, but for mobile computing I'd rather have 15 hour battery life, software / hardware harmony, and be able to drive to an apple store for a replacement when my nephew spills apple juice on it when I'm out of town visiting family.
Another thing; supply chains are still really messed up. You're looking at 4+ months lead time for a custom Thinkpad right now. Just something to consider.