I've ridder both the Look Keo and Time RXS carbon. Time was much better for me. Here's why:

The Look cleats were "unstable." It's hard to explain this correctly, but the center rubber piece of the Look cleat that actually touches the shoe is not wide enough and can cause some "rocking" motion of the shoe. This probably does not happen to every rider since a lot of people like the pedals. I had problems with this and had to stop using the pedals.

Time also has the advantages of easier clip in/clip out (once you learn it) and pedaling also feels a bit more efficient (this could be my imagination though...).

If the Looks work for you then they are the cheaper choice. Time worked better for me.