Travel Agents work but have some disadvantages in terms of impacting performance and feel. Note how the instructions for them repeatedly mention making sure the cable is firmly seated. That's because if it isn't, it creates slack that translates to wasted brake lever movement and squishy feel. If you're careful you can set it up to avoid the worst of this, but there will still be a non-zero amount. On that level mini-v's tend to work better if you're only looking at it in terms of power and feel. However, mini-v's have the major disadvantage of throwing away tire/fender clearance on most bikes. They're only really good if you want to be using the kinds of tires they play nice with.
One of the things about this question people often refuse to understand is cantilevers are by definition able to offer power that linear pull brakes can't. With cantis you can make the mechanical advantage be whatever you want. Meanwhile on linear pull brakes, for a given brake on a given bike you're stuck with whatever mechanical advantage proposition is offered by where the pad is falling in the slot. If raw power is the goal, on a drop bar bike that needs its tire clearance, wide-profile cantis set up with a very low straddle and a stiff cable hanger at the fork crown are hard to beat.
