Another important point is the Taurus is a dead and discontinued car,
I would shy away from a newer one and buy a cherry from a few specific more reliable Taurus years if that is what your heart is set on.
Wouldn't bother me in the least. They are cop cars and that alone should mean parts availability for the sedan specific bits will remain high. The rest of the drivetrain is shared with the Explorer (AWD, brakes, etc) and the Duratec 3.5/6F500 has been made for years so those bits will be available for a long time too.
The Impalas are nice vehicles as well. An Avalon or the Genesis would be about the next closest competitor in size. The others (Mopar) are just as dead and dated and with less reliability to boot.