I was in the market to buy a printer that I wanted to use with Linux. I looked at the compatibility chart for Epson printers. Every single one is supported. Made my life easy. True to form, it worked out of the box. Avahi found it. Used the Cups web interface to install the driver. No issues.
On the topic of supported platforms, when I bought a new laptop, I went with Toshiba because, at least with the Japanese models, every single one supports Linux.
The fact that I can buy new, off the shelf equipment and have it work on Linux with no issues is really what is new for me. You still have to do your homework, but I remember the days of having to look around for used equipment to make sure that it would work with Linux. Those days seems to be over.