shepper
Brother has (at least for some models) also Linux PPD files for download. However, what
Oko said above, applies fully. There was a PPD file and a bash script that had to be funneled into cups some hackish way.
I wasted almost two hours trying getting that work on FreeBSD to be able to use a Brother printer at the university. But as I realized all the stuff Oko described, I ditched the idea to use the brother at that workplace.
f150_raptor
Regarding the Kyocera printers I currently use:
They an older high-end series of the FS-C5xxxDN color printers. So they have all, usb, ethernet, various interface modes (IPP, LPD, Appletalk etc), PCL6, Postscript, duplex printing, additional high-capacity paper cassettes, etc
And they are fast, up to about 20 double-sided pages/min in full quality color mode.
The Kyocera-supplied PPD file works flawlessly with FreeBSD.
I bought two identical high-end models for 30 euros each in good used state from a commercial refurbisher. I bought two, just to have a backup and spare parts in case.
S&H was actually more expensive than the printers themselves, as each one weighs 30kg (the additional paper cartridges not counted).
Toner is very cheap, too. Just buy unused leftover cartridges at ebay from people that bought a new printer. This way I pay about 20% of the new price, for original toner.