Which Is The Best Restaurant/pub In Dartmouth?

the Kings Arms in Dartmouth is well known for its sea food and wine list, so you should be happy eating there. They should be able to take a larger party, but its a good idea to book in advance in the south, especially in country setting on a Sunday. You could do this on line www.kingsarmsdartmouth.com.
Another option not to far away, is the Sticky Prawn which specialises in seafood, and of course prawns.
It depends what you want to eat of course, but they both have a good range and are not too pricey, since you asked for a pub/restaurant.