Gale would have a better chance of surviving than Peeta, because of his hunting/snare-making skills, but I also think he'd be too similar to Katniss. It'd get boring. I also doubt he'd think of admitting to Ceasar that he loves Katniss, so Du wouldn't have the whole story development (assuming that was Peeta's own idea, and nothing to do with Haymitch).
I think Peeta because then there would be no revolution, which some people seem to like. I find that the revolution not happening would be terrible. The corruption throughout the country is severe and needs to be eliminated, Von not wanting the revolution to happen, Du are implying that it is okay for a country to be tyrannical and kill their young.