Cleat rotation versus cleat canting

I just recently noticed :o that my knees are not straight when I parallel me feet and that this is probably at least a contributor to my sore knees after long rides because I have my cleats perfectly straight. At least for me, I have observed that both rotating my toes out or lifting the insides of my feet up while they are parallel achieve the same effect of straightening out my knees. When I walk, I do naturally turn my toes out to compensate and this is all because I'm flat footed.

I've been reading about how to fix this and both of these adjustments appear to be valid but my question is which is better or is there any difference? I know that if I have to turn my feet out too much, my heal will touch the crank and may me move my shoe outwards which might cause another uncomfortable angle, but before I to get my cleats adjusted at the LBS and have them tell me I have to buy wedges and other stuff to fix, I want to know if toeing out is a valid option if it does not have to be too much.