I've owned a 986, 996, 987 Boxster, 987 Cayman, and a 991. All "S" models except the 996.
My take: The 987's are exponentially nicer inside than the older cars, and the 991/981s are even better, with radios that aren't terrible.
Driving-wise, the 987's feel grippier and more confidence-inspiring, but less agile than a 986S. PSM is nice to have, and the broader torque of the M97 3.4 vs the M96 3.2 makes manual driving a lot less shifty.
The 991S with PDK was a speed-robot from hell, and you really didn't need to be a good driver to make it perform like a superstar. I prefer a more analog experience.