Originally Posted by DanH
A plate chiller is a type of counterflow chiller. To do both wouldn't be much different than getting a PC with more plates or a CFC with more length. I would just get the largest plate chiller you can afford and run the wort trough it slowly. I like my PC because it's small enough to mount to the single tier frame out of the way and it works easily. Cleaning isn't as bad as I had thought it would be either. It's all up to your preference though.
Keep in mind that the temperature of the cooling water source is the determining factor as to how quickly and how low your chilled temp will be. In the winter the ground water is much colder so things will go faster and lower but in the summer you will need to restrict the flow in and not get as low due to the higher temp.
For example, I use a CFC gravity system, in the summer when ground water is around 70 it takes me about 30 minutes to drain 6 gallons to 70 degrees but in the winter it takes me 10 minutes to drain 6 gallons to 57 degrees.
The only way to equalize things in the summer is to use a pre-chiller for the water source which would involve another vessel packed with ice water. You can then use an IC chiller in the ice and run the wort through that first and then to the plate chiller. It all depends on how much you want to set up and deal with.