I can't find a correlation in my memory to which time of day has been best.  It seems to me that the time of day may affect where I fish, though.  During summer in my home lake, I love to flip the docks.  However, during early morning and late evening, or if it's real cloudy, bass tend to be roaming around instead of being tight to the docks.  So, my best time of day there is right in the middle of the day when the sun is real high.  But, this goes back to the 'sweating to death' point.  I barely got out in mid-day this year due to the ridiculous humidity and lack of wind.

Mornings are usually better than evenings, but I am definitely not a morning person so it;s evenings for me.

In hot Florida months I like evening fishing because its a lot cooler when you have to load the boat after fishing.  In the cooler months I like morning fishing because the loading and the heat are not a problem.  Both evening and mornings have low sunlight conditions, and excellent fishing.  Those are magical times.