Watts........Watts are good. It is what I studied in college in a lot of different forms, from entry level to advanced. Watts is what has built my house, put my kids through school and hopefully will allow me to retire to generate my own watts. We have an exhibit at work for the general public to use that will give you a really good feel for how watts vary. We've put a hand cranked generator on a board with a switch that can connect a variety of loads from a 25 watt light bulb to a 1200 watt hair dryer. People almost break their arm when the switch is thrown over to the higher wattage devices.

Watts is simply the work (or effort) being made. Energy is a measurement of work over a period of time. Watts is a great way to measure effort because it removes all the variables-wind, speed, cadence, heart rate etc. Assuming the device is legit, it provides you with the true effort you're making and is the best way to train. Most devices use algorithms that simply take the data and "estimate" the wattage based on the inputs from the device.

Personally, I cannot generate that much wattage compared to a lot of folks because I have power to weight constraints, but I'm pretty good at expending a lot of energy on a ride because I can hold a particular wattage for a pretty long time.