Based on your actual experience with each, what are the pros and cons of the two most common types of wort chillers - immersion and counter-flow? Which do you prefer?
The Immersion Chiller is easiest to clean and the most reliable from a cleanliness standpoint. The efficiency and speed of chilling can be a bit troubling sometimes depending on the water from the taps temperature. You also have to dabble a bit in flow rates of the water. I find that I can run the water fairly fast for the first few minutes, but I really need to slow it down to maximize heat transfer as the wort cools.
A counterflow chiller (and also plate chillers), are often but not always more efficient at chilling. The are however usually completely sealed up. So cleaning can be a bit worriesome if you don't know you have a deposit in there. Also to prevent deposits and clogging with plate chillers, you really need to seperate hop debris from the wort as it exits the kettle. Depending on the style of counterflow being used sometimes a pump is required for good wort flow.
I too will be upgrading to a whirlpool chiller soon once I get my pump up and running. I guess that means I prefer my immersion chiller. I use a 50' 1/2" copper coil setup.
I can chart a few big leaps in my homebrew quality over the years. Switching from immersion to counterflow was one of them. Getting a good cold break makes your beer clear. CFC use less water.
My next chiller upgrade will be a whirlpool chiller.
I started with an immersion chiller and then went to a plate chiller, however I still use the immersion chiller in line with the plate chiller like this: http://backyardbrewer.blogspot.com/2009/08/post-chiller-chiller.html
which helps a great deal. mark