ive used mylar, and the silver reflective sides of grow tents, tin foil and just flat white paint(in the u.k we call it emulsion) and i would have to say that i never had problems with any but i'd kinda recommend the paint coz its cheap and easy.
Anything is better than nothing. Black and white/panda is easy to work with and cheap. Film is the best hands down. There are different grades of film and the cheap is messy to work with. I use both panda and film, the film is better and I find growth around the edges where the film is fuller. I use a staple gun to put it up and put a piece of duct tape where I put the staple through to give it more holding power. I also keep it about a foot above the pots so water does not get splashed when watering. I have had the same film up for 5 years.