The reason your question cannot be answered is the fact of blade angle. It is not the rotation you are looking for but the direction of air flow. Usually you draw air UP for heat. This will allow the fan to raise the cool air to the ceiling then mix with the hot air at ceiling then the blend of air will come down the walls back into the space. If you blow air down in the heat mode you will create a draft where you are sitting and be uncomfortable.
Whichever rotation you need to use to be comfortable is your decision.
My vents are in the ceiling and this is what I use. Now when you really get down to it the difference is not that substantial anyway. All you are doing is moving air to blend. Now if you have 30 foot ceilings to worry about that could be a different subject but the average home there is not much difference except as already mentioned for comfort. I suggest a variable speed control since running the fan at slower speeds usually work well.