Fiber optics Vs. Cable internet

I've currently been using Comcast cable internet, but recently Qwest has rolled out fiber optics in my area. Comcast offers 20 Mbps downstream for $19.99 introductory then $45 after 6 months, whereas Qwest only offers 20 Mbps upstream fiber optics for $49.99. I have a roommate that shares the internet with me and we both use it for high traffic activites such as downloads and online gaming. My question is: Which would be best for me, fiber optics or cable? I am looking for an option that provides the best quality connection that won't drop off during peak hours of the day (if possible), as cable does. I don't know too much about fiber optic networking versus cable networking so I was hoping some one could point out the pros and cons of having either.

Personally, I would go with Qwest. I use Qwest DSL and I'm not aware of any bandwidth throttling. Also, the way Fiber works is not a networked neighborhood like Cable is. So, instead of hitting the mid afternoon bog down, you should be stable through out the day with fiber/dsl.