I am going to give my observation on playing with different pick sizes,stiffness and thicknesses.
I,personally have discovered that it requires a certain degree of playing skill to play with a smaller size pick(i am using the standard universal style pick,red green purple above,as the default).Once you begin to get smaller in size,it requires better playing skills.Also,the stiffer the pick,the harder it is to execute playing rhythm.And...the thicker the pick,the harder it is to control and execute accurate solo playing.Most players use the standard shape pick,in a medium gauge.Again,if i was a beginner,i would choose that shape pick, in a thin or medium gauge.Then once i got use to that particular pick,i would maybe move on to a smaller size.Then once i was use to the smaller size,i would increase the thickness/stiffness.
As a general rule for me....the heavier the gauge string(acoustic guitars),the thinner the pick i use.And the lighter the gauge strings,the thicker and smaller the pick i can use,accurately.This is just for me,you may find better solutions for yourself!
So...for beginners,i recommend the standard shape,in a thin or medium thickness.Then,if desired,move on to smaller and thicker/stiffer picks.
