I find a strat less comfortable to play, and I learned on one, I still use my strat copy's neck on my home made custom job, although I attacked it with a belt sander. The scale length of a fender 25.5 inches, is longer than a LP's which is usually 24.5 inches, this makes string bending on the strat harder, also worth bearing in mind is the distance between the nut and capstan on a strat, so the higher strings are even LONGER (this is why I prefer reversed headstocks) and a les paul has 3 on each side. I'm not a huge fan of the twangy sound of a strat, I prefer richer tones myself, but I wouldnt say a strat is any harder to play.
It depends on the music really, if you wanna play some twangy funk like red hot chilli peppers, a strat is the better tool for the job, but some sweet pentatonic solos like slash just NEED a les paul to sound right

(I play a BC rich, what do I know?)