We've eaten at both & they are both great!! WG is more of a "restaurant" feel to it, nothing special in terms of ambiance but the food is very good...different from a lot of the steak/chicken dishes served at most other DW restaurants.
RR has great ambiance (if you like the dressed-up pub feel) with entertainment if you eat at the right time. Their food is more "comfort" foods like fish & chips or bangers & mash but it was very tasty.
We would not hesitate to do either agian but I think if we had to do one or the other, we would choose Raglan Road.