Use whatever is easy to maintain. I like white paint for that reason. Also makes it easy to see if there are bugs on it.Ok Wall coverings... Mylar, Orca, reflextex what's your choice.... And why do you like it... Pros\Cons
Currently I have white paint and I'm looking for measurable differences...
I wouldn't waste any time chasing reflective surfaces for how much extra light they will add to your grow. Inverse square law says that even a perfectly reflective surface is not going to deliver much, if any, usable light - distance from light to wall to plant. Becomes even less useful when you switch to LEDs and stop throwing light on the walls in the first place.