To elaborate on that complication -
Certainly the obvious answer to this question is "what competitors?"
However, even if we had a competitive panacea - say, a commonly held, local government managed last mile over which you could connect to dozens of ISPs, all competing for your dollars - we would still not have a truly competitive environment for one reason: price signals, or, rather, the inability to communicate them. Before we conclude that a market can solve a problem, we have to make sure that the structural prerequisites for a functioning, competitive market are in place. One of them is price signals. And I mean this generally.
So, the way this argument usually proceeds is to say: "don't like a tiered Internet? Well, if Company A doesn't follow common carriage principles, and Company B does, consumers who are sensitive to net neutrality will utilize B over A, putting competitive pressure on A to discard a tiered Internet and embrace net neutrality."
But there is a simple reason that this oversimplified model doesn't work. I don't need to run a traceroute for anyone on Slashdot, but most people (especially people who make the argument above) don't realize that when data moves from point X to point Y on the web it also passes through a half-dozen networks besides. And the experience of the consumer is not only affected by their ISP, or the ISP of their content provider, but also by the intermediary networks.
The problem, from a market solution perspective, is that *there is no way for the consumer to communicate their preferences via price signals to the intermediary networks.* Perhaps the consumer opts for (network neutral) ISP B, and their chosen content provider is on (network neutral) ISP D. But if their data have to pass through non-neutral ISP C, then their access may be degraded, and *they will not have a way to choose a different competitor*.
This is emphatically *unlike*, say, contracting FedEx to pick up the package from your house and deliver it to your friend's house, with all of the intermediary travel handled by FedEx (and thus subject to the competitive pressure of your decision to use FedEx rather than DHL or UPS).
Once you begin to screw with the haphazard egalitarianism of the present architecture of the Net, you begin to run into all sorts of problems like this. So beware the arguments that "the market" will solve everything! The market is a powerful machine, but it is a machine, and when parts of it are broken or out of place, it's just as unusable as a car without an engine.