Next2 is one of the best in Positano! The maitre'd helped my wife design a dish which was a combination of their specials and it was delivered as ordered! They even filleted her fish at the table - a work of art. No effort was too much. Friendly, efficient service and very tasty food! Good selection of Italian wines. Nice seaside look with white furniture and walls.
Be prepared for a relaxing stroll up the hill to the restaurant (and back down afterwards!). Taxi's are available, but it is actaully very nice to enjoy the sea breeze and the tourist buzz.