From my experience doing both, flying with seized rotors becomes very boring after a short time. All airports look the same after all and the cruise portion (95%) of the flight offers little redeeming value. A plank career obviously has the potential of leading to one of those jobs where your taxes will be more than most helicopter pilots' entire salaries. But as in everything, there is a price to pay first.
From a "Joy of Flying" perspective (or Zen if you are that way inclined) rotor craft win hands down for me. A joy ride in an L33 can be fun, but as a full time vocation there is no flying like helicopter flying. It has an endless variety of activities to keep even the most jaded on their toes - logging, construction, scenic, EMS scenes, off-shore, SAR, ship-to-shore, VIP transport, luxury yachts, UN missions etc. etc. The list is endless. Last but not least, we often find ourselves developing relationships with our customers which last well beyond the job.
The flight pay may (justifyably) not be on par with airlines in general, but for the ambitious there are still good money making opportunities in the helo business as well. Logging, overseas and becoming a small operator are some that come to mind.
So I'll stick with the greates flying machines ever invented. I like being able to stop BEFORE I land.