Both are of similar efficiency, so there should not be any noticeable difference between the two designs. Other factors will play a much larger role, for example farm location, player position, and spawning spaces.
If I had to take a guess, I would guess that design 2 is slightly less efficient. This is because mobs in the corner will be unlikely to pathfind to another quadrant with just 1 attempt, as they are out of range. This means they will require at least 2 pathfinding attempts before crossing the water instead of 1.
You can induce mobs to pathfind more frequently by providing more solid blocks around them. Mobs pathfind to nearby solid blocks, so if there are more nearby, they will be more likely to pathfind. You can even exploit this by only placing solid blocks in areas you want mobs to walk towards, and making other places out of non-solid blocks (glass, slabs, stairs).