I've put Ubuntu on many things, from beefy laptops to netbooks to part-scrapped desktops. Seldom had I needed to fix driver issues. So my advice would be to search in the opposite direction: find any laptop that fits your budget/specs and then search online if there had been any issues installing Ubuntu on it.
I have a 1yr old System76 Galago UltraPro. I like it, works well, fairly quiet. Purchasing experience was good, even with importing to Canada. My two problems are 1) it will occasionally (once every 2 months) experience a power loss and reset the laptop. No clue as to what's happening, so infrequent that I don't care to look too deep, 2) the wrist rest finish is rubbing off in the corners, looks dirty, but it's just the black plastic showing through.
I've had good service from the Dell XPS 15z I am typing this on. It is now over 3 years old.<p>I set it up to dual boot Win 7 and Kubuntu. I kept Win7 originally for gaming. I think I booted to Win 7 1 in the past year. There is even less need now with many Steam games working on Linux.<p>The Optimus(?) graphics system split between Intel and Nvidia was an issue initially. I played around with Bumblebee a bit but mainly have just used the Intel GPU as it provided better battery life and I haven't been doing anything graphically intensive.<p>The only unresolved issue is that the external HDMI port will only work if plugged in a boot and exclusive to the laptop screen. There may be driver fixes for this now but I haven't had the need so haven't checked.<p>I have also successfully run Ubuntu variants on Thinkpads (T series) and a couple of Asus Atom netbooks.
I would strongly recommend looking for a used 2013 MacBook Air (non-Retina). I used Ubuntu on one of those for a while. You should be able to get one reasonably priced directly from Apple at this point.
I am using a used ThinkPad. Great keyboard, great community around the ThinkWiki, Ubuntu certified hardware, much cheaper than new, solid stream of replacement parts at reasonable prices.<p>Good luck.