Aluminum flywheels
 

What is the best deal around for one and the pros and cons

Not many significant pro's or con's and all are difficult to validate. I am using alum...but probably wouldn't do it again. There are a lot more drive train items that bring more valve.

Used all the time on high revving road racing cars. Lighter flywheel allows the engine to rev faster. You do not want one for a marine application or drag racing. Standard weight is what you want to use.