I recommend froakie due to its immense versatility with protean. You can completely outpredict the AI and transform into a type that resists/is immune to the incoming attack. You also get STAB ERRYTHANG! Of course, the only water type starter on your list that is capable of not being weak to Queen Boomy is froakie as a well placed round takes away your water type and a well timed lick can prevent a harmful explosion attack from voltorb and electrode. He gets amazing coverage late game with moves like water pulse, night slash, extrasensory, and grass knot. Of course, an easy way to defeat Radomus due to that dark typing and Shade as well *shivers*. Let's not forget, he's also super effective on many leaders to come, such as Terra, Charlotte, and Hardy. But for sure, you won't have many regrets grabbing froakie as your starter.