Dave wants to know what phone would be better: the Sony Xperia Z3 or the Samsung Galaxy S5. Leo says that the S5 is waterproof like the Z3, but it has a better camera. Leo adds that TWiT staff have tested the S5 and it's pretty good. There's a test video of a third party testing both phones here. He can check the waterproof rating (IP number) on each to make sure. That will tell him exactly how water resistant it is.
Nothing is perfect, though. He still shouldn't go swimming with it or put it in a glass of water. And he should remember that real life is far different than laboratory conditions. But if he's in the rain and wants to take a picture, he won't have to worry about it.