Acer seems to support all Linux versions perfectly. But c720 is so ugly.. :( Any views ?
Keyboard is good, but it doesn't have a delete key or a meta key (this might be true on all chromebooks). The touchpad is above average IMO, but it doesn't seem to work great in Linux (haven't tried tweaking it yet).
Know that running linux via crouton can be a pain in the ass if you're used to having a full-blown linux install. If you want to be in Linux > 50% of the time I'm not sure I would use crouton, you could maybe explore the dual-boot option which I haven't tried.
Overall it's great for my purposes - most of the time I'm just in Chrome or sshed to my DigitalOcean box. if I need to do something else with a real OS I can switch over to crouton. Super cheap, it's super light, and the battery life is great.
https://www.google.com/work/chrome/devices/hp-chromebook-13/
Unless you are really looking for the lowest cost possible, I would suggest that a more mainstream notebook will be give you a better experience.