It really depends which one is better for you. It varies for us from trip to trip, actually. It depends on my ADRs, mostly. I make ADRs as early as possible, and then I literally figure out how much our meals will be with our TiW card and compare. Lately, we have been using both the DDP and TiW.
Important FYI- you can also apply the TiW discount to things not included on the DDP! For example, any appetizers and adult beverages will receive the TiW discount, even if you are using DDP credits for your meal.