I've used SPD's, Look pedals, and currently the Speedplay X2's. I'm not familiar, unfortunately, with the TIME pedals...perhaps another member knows something about them.
By far the most popular road pedal, at least among the cyclists I've seen, are the Look pedals, which come in various versions and weights. They're very easy to clip into without looking down...you merely slide your shoe forward until the cleat stops and shove down. The red arc cleat available with Look pedals allows a little freedom of movement (float)...The system is very good and appeals to a wide variety of people. I currently use the Speedplays because of knee problems; they allow a great freedom of movement and seem to reduce the stress on my knees. The SPD I'm familiar with only on my mtb...they seem a little harder to clip into than Looks. Their main advantage seems to be a low profile that allows easier walking in cleated shoes.