Ubuntu tends to have a list of hardware[1] that plays well with it. From my personal experience, I've had good luck with Thinkpads and Dell precisions.
I've had good luck as well. But I would so much rather have a supported hardware platform rather than luck.
Possibly would be even better if they sold the hardware themselves. Just resell one or two laptops and fully support them for the duration of the Ubuntu release.
I've consider the dell developer editions (the ones that ship with ubuntu) to be sort of official ubuntu laptop (I got one last year and the experience has been pretty good). But I agree, I'd always welcome more laptops that are linux friendly :)
[1] https://certification.ubuntu.com/desktop/