Compression, Sweat, and Threaded Fitttings: The Pros and Cons

OK, all you guru plumbers...I have found this site and all your advice a great wealth of knowledge indeed! But what are the pros and cons of all these different valve fittings? Why should I choose, or not choose, a compression fitting over a sweated or threaded fixture valve? What happens when a compression valve fails years from now; does the ferrule need replaced as well? I've read to use sweated supply valves and compression fixture valves, but why? Is the final answer just 'user preference' or are there specific reasons?
Thanks...you guys are great!

Sweating a valve is permanent. It usually leaks immediately if there is an improper joint made, but that is not always the rule to follow. Threaded valves have their place, like in a meter bracket setup. A threaded connection is pointless without a union in front or behind it to remove/repair/replace down the line and the only time I install unions are on water heaters (Dielectrics). Every union that was on a copper water line never gets used again because they never match up old to new on the sizes of tanks. I use compression angle and straight stops on most applications involving copper piping unless an older house has 3/8" IPS brass nipples serving the fixture. If I know of an area that has horrible water quality I will sweat 1/2" male adaptors onto the pipes so that the valves can be removed easily by the homeowner. Brownie Points!

valves

The application usually determines which types of valves should be used. The final decision, however, depends on the experience and abilities of the one who is going to install it.