I think we will need a mix of everything because no single type is perfect on its own, i.e. solar depends on the sun and wind depends on the weather. We will have to be very smart about making them all work together in one big system that can give us power when we need it.
One interesting possibility people talk about is bioenergy with CCS (carbon capture and storage). The idea is that plants capture carbon dioxide from the air, and we then cut them down and burn them in power plants – but we capture all the carbon dioxide released during combustion, and store it deep underground. Because we have effectively taken carbon dioxide out of the air, the greenhouse gas emissions are actually negative. So we could get clean, reliable power, and actually undo some of the effects of our emissions so far! If we can ever get that system to work (without destroying forests), that would be great 🙂