fm7 is easier to use...but i get much better sounds out of absynth.
but, i have not used absynth 3 yet. if you are looking for something very
easy to use and some decent sounds...check out the pro53..especially
if you like square and triangle waves.
both are good, but are not really comparable
they each have their own sound
but if you're looking for more challenging stuff soundwise, then check absynth, download the crack, and check it out for yourself