Initially I thought this was a silly question until I remembered the golden rule of business..... create your own competition. When you do that, no matter what site of yours they go to, you still win. Its like casinos in Los Vegas, so many are owned by the same person, and one casino might fit your personal style more than an other one owned by the same company/ person.
The best part of the likeness between some of these sites and casinos, they are still going to walk with your money. Not all companies, but some.
Be Happy,
DW