Sorry Davids I just saw you post. The answer is not straigth forward, because it depends very much on your chest thickness and limb length.
The people I know that really like floor presses are thick chested, short armed power lifters. When in the bottom position the bar is nearly touching their chest. Floor presses for these guys simulates the pause performed in a PL meet and you don’t have to release the weight to hold the long pause. In a rack press, the weight is taken entirely off your hands and you have to press against a dead weight. I like rack presses because they are safer, but I like board presses better than either of the two above, as do most PLs I know.