Cantis are fine.
With the advent of Koolstop Salmon pads, I get fantastic, if not better stopping power than with disc brakes. I was able to stop well in wet conditions or with additional weight going down an 8% gradient.
It would be different if you were on a tandem bike. Even if you have disc brakes, you need to stop for a little bit to allow the rotors to cool.
Cantilever or Linear/v-brake work great with Salmon pads when adjusted well. You could opt for disc brakes, but it's entirely up to you! Either way under heavy braking you either will need to stop briefly to let the rim cool or let the rotors cool.