i also vote for the siwys, also smaller pockets make butt's look "bigger"
Example quaalude wingers (girls complain these flatten their ass)

Vs Amethyst Scorpions (pockets for flatter bums)

The people's liberation I own seem to have larger pockets and the "flattening" effect

I don't know if matics really give me more bum, but they look feel nice ;D

So cut is important and I think color does too... lighter shades have a "maximizing" effect while darker colors are more slimming (i think we all kinda knew that)
Hope that helps... need to update w/ the siwy's and chroma crops.. :P