From what I've heard, the red wine club is the one to go choose. Don't let me stop you from experiencing that, because it's a cool way to experiment with wine.
With that said, here's my story with the sauvignon blanc club:
- gave to my mom who didn't like the non-sauvs (she had to pour out two because they tasted mushroom-y, though they may have just gone bad), and said the sauvs were "drinkable but not worth repeating"
- wasn't aware my 3-month club membership renewed, and after being charged for another three months, was only refunded part of the amount (most memberships warn you about future renewals and how your card will be charged X amount, giving you a window to opt-out; not so with Plonk)
- Satisfaction guarantee is questionable. One of the bottles arrived with the cork halfway out, which Etty (email) / Meredith (phone) promptly replaced, but after I commented on how one of the wines may have gone bad (I mentioned "mushroom-y") and if she had any solutions, she ceased communication. That was two weeks ago and I haven't heard from her.
Moral of the story? Go for the red wine club, don't expect any customer service, and if you don't want your membership to renew, email or call (repeatedly if necessary) until you get the answer you need (and get it in writing). Here's hoping she responds to you.