well, whichever way feels better to side hop or the way you spin. before I ran pegs I found it easier to hop up a ledge on my left than on my right, and I spin right. therefore I run my pegs on the left.
If you rode your bike more often you might not have to ask the internets.
try hoping to both sides and see which is more comfortable
That seems like the easiest way to find out which feels better. If they both feel well, then you should ride four. I'm left foot forward so I first put pegs on the that side for two reasons; it wasn't on my drive side and it gave me the most room to not be standing on peg or clipping my heel. I put some on my right side a little while later and it just didn't feel right.
The way i see it: most people can grind a ledge of rail with pegs on either side of the bike...so base it off the way you regularly spin 180/360 etc i spin to the left so i keep the pegs on the right side of my bike so that when i go to grind quarter or something (which involves some spin unlike the ledge) it is easier to rotate onto it. i hope that make sense simply put: if you spin 180's to the left put the pegs on the right side and visa versa