I like drive modes if there is a perceptible difference.
In my wife's SUV, for instance, the sport mode miraculously makes the whole thing seem to come to life. Throttle response is dramatically different, the transmission holds a gear (or two) higher for much longer, etc. On the other hand, the eco mode is also noticeably reserved and almost feels like there's a cylinder deactivation (which there isn't). I usually default to sport mode, but honestly, it's a little hairy for something like the drive to school.
IIRC, the M button in my E63 M6 activated 2 addition cylinders for an extra 100hp over the norma, default 8-cyl mode. Beyond that, you could program the other settings such as traction control and transmission shift speed so the M button was a one-stop-shop for excitement
- again, a very noticable change in the car.
It seems the drive modes become more appreciable if the car has greater performance... there's a lot more bandwidth for change when you have, say, 500hp rather than what you can expect to change in a 150hp economy car.