I have been on a number of toll highways and can say that in most cases those highways are maintained slightly better and tend to have more lanes. With that said, I prefer free highways, because I find the toll booths annoying on toll highways. I do not enjoy having to pay an additional fee, nor do I enjoy having to navigate the toll booths.
In Denver we have one major toll road, E-470. I avoid taking this road because the cost is absurd. The last time I drove on E-470 it cost $11.00 for a round trip. I simply can not imagine that people are able to pay that much to commute on a daily basis. Our other highways I-25, I-225, and I-70 can be congested during rush hour, but at least they don't cost $11.00 a day.