Golden Retriever. Why? He's smart, super easy to handle, and great family dog. Hunt ducks, geese, and all the upland birds too. He's steady to flush and shot on land also. Couldn't imagine hunting with anything else. I love my multipurpose/multitalented Goldens.
Far as varmints go Ive got a little beagle girl that is heck on bunnies. She came to us we didn't seek her out. Father in law loves a good beagle and helped get her started after that it was all education in the woods. 13" but she's all heart.
I've also seen a pair of beagle x Jack Russell Terrier crosses that were unreal. Totally fearless, will run till their heart gives out, and nothing, I mean nothing phased them. They were an oops litter but I tell ya that was an oops Id like to see again. Terrier heart and mindset with the nose of a hunt. Varmint getting machines.