Like Brian Sr said. It's all personal preference and what feels good to you. I play either position depending on mainly two factors. Is it comfortable and does it make the part I'm working on harder to play? With my Ibanez RG which is a smaller guitar it fits and feels better playing in the classical position. I find playing in this position makes larger fret stretches easier. Where I would have a pretty easy time making a 1-5 stretch over the right leg I can easily make a 1-6 fret stretch in the classical position. With my Schecter E-1 an explorer shaped guitar which feels humongous compared to the RG I can't comfortably play it in the classical position because of the upper horn forcing me to practically do the splits just to get it in a comfortable position that isn't very comfortable. With the upper horn being there I've noticed the neck sticks out a ways more which makes me raise my arm a bit more so it isn't as comfortable as the Ibanez to play lower fret stuff as say 8th fret and lower stuff. I haven't had an issue playing a techniques in classical position with the ibanez. Others experiences may differ so you'll have ot figure that out yourself! Different guitar body shapes may have you sitting differently to play them comfortably. Good luck playing a Flying V over your right leg like you might with a Les Paul shaped guitar. Anyway before I ramble on more and more I'll end it there! Hope this helps man!