For stillwater boat/canoe/pontoon are the best. Easy to operate and make it possible to quickly move to a different spot - follow fish and cover a lot of water. In many situations you can use wind to your advantage. On the fast moving water the boat would be better if you were to anchor it everytime you try to fish or have somebody drive/steer for you.
I have little plastic boat http://www.jowatercraft.com/Bass9.4.html which is extremely stable. I can get it loaded and off the trailer in less than 5 minutes so the prep time is no an issue. I have no problems fly casting from it and steering/controlling at the same time. Use of dual anchor or drift sock further increases possibilities of fishing.

However you cannot forget that sometimes there simly is no choice but to walk and wade. Most of the trout streams around here are too small for any sort of floating (other than dry fly).