We use Sams most because it's closer. Been a member for 15+ years. True what Ladyhawke said. I'd push you toward Sam's. You can pay off the membership easily.
The thing I do like about Sam's is it seems like there's always a deal to get a membership for about $25 after a gift card and coupons for free foods. Might have to bite... only thing I don't like is it's farther for me.