The speed of both will be similar.
If higher CL speeds are available, it's a safe bet you'll be overprovisioned to 9 Mbps. Comcast will
overprovision to 6.6 Mbps. Overprovisioned CL 7M will be faster.
Since the prices are similar, the rest of the decision would come down to local factors. Comcast is good (as good as they can be, at least) in some areas, poor in others. CL is good in some areas, poor in others. In my area, for example, CL provides great reliability while Comcast can't keep their network up for more than 5 minutes.
Your best bet would be to ask neighbors and see what their experiences have been.