for budget conscious and long range riding requirement, I would go with the gas motor. if you have the money I would go electric. and of course, go with the lawful one. in terms of operating, for me it was about the same - pedal to 8-10mph, turn on power, and go. I pedal even on electric to help the motor overcome inertia and save power. speed wise the gas will exceed 30 mph if properly installed and 1000w electric will be just at 30.
gas pro - cheap, long range (gas stations, one tank = 60-80mi)
gas con - lotsa maintenance, random quality on engine&parts, rear wheel wear, chain maintenance
electric pro - no maintenance, reliable, low wear on bike, no gas/oil, no noise, usually legal, easy to install (less than 1 hr)
electric con - expensive (lipo batteries), limited range, no gas station,