See also thread How do you keep your feet dry?
My choices are limited with big (13EE) feet. Before I coughed up money for a pair of SIDI's I was using SPD sandals and Seal Skin waterproof socks. This was my winter setup for Nebraska and proved acceptable for all but high impact water. You can't lift your feet EVERY time you have to go through a puddle and this is where they failed consistently. Oh, and Seal Skin socks need to be laundered and dried gently but frequently.
When I found the Carradice Pro route rainwear I found absolute wet weather protection. The Spats are my favorite: they go over the shoe and cover up to your knee. The zipper is on the very back and the underneath is open. It blocks all water but is not submersible.