My perfect day would be determined by what fish I’m trying to catch and how I am going about it. If I’m aiming to catch largemouth bass I would prefer a relatively overcast day, so the fish aren’t instinctively pushed lower in the water column and into cover to hide from the sun. For any type of fishing its best to have little to no wind because it makes it easier to control and aim your cast, and if you are fishing bottom baits you are able to watch your line for movements that indicate a bite. If I’m fishing for carp I would prefer a nice sunny day, I don’t know if its true but I seem to have better fishing on a sunny day rather than not. And when I’m carp fishing I’m mainly sitting and waiting for a bite and it would suck to just sit in the rain.