what is the best radio controller unit for a model boat?

I have just started building a model remote controlled boat, and I have yet to purchase a RC unit and servos etc.
Does anyone know what a good entry level model that will be still useful as I progress?

for a boat you need at least 2 channels to start with so any of these will work
if you want more things to move look for a 4-6 channel radio for serface use
have fun
Dan