What is the best spark plug? HELP!

I have a 2000 Grand Prix GTP. It's bone stock aside from a fender cold air and a cat-back exhaust. I also lost a few pounds from my mid-section to help out with weight reduction.
This car is a daily driver, but I love the looks on ricer's faces when I disappear off the line. I'm toying with the idea of getting a smaller pulley for the SC, but I'm still on the fence.

It's time to change the spark plugs and wires on the beast and after all the reading I've done, I've come to the conclusion that Autolites seem to be the most popular. The questions that remain unanswered are:

What core metal is best for my application (copper, platinum, iridium...)?

And should I stay with stock temperature, or will dropping down give me any advantages without any negatives?

Any help, thoughts, advice, direction, would be most appreciated!

I'm going to research this more, so don't quote me, but the type of metal used effects the longevity of the plugs, not performance.

Most people have a chart for recommended drop in degrees for spark plugs, which is dependent on the amount of modifications you have.

Also,
http://www.automotiveforums.com/vbulletin/showthread.php?t=900625

Just changing the pulley won't do much good (and will actually increase the chances of engine damage) without the other supporting mods like a reprogrammed PCM, 180 degree thermostat, and the colder heat range plugs you mentioned. If you race it and will be checking the plugs and changing them often, go with the copper core Autolites because they are cheaper. Otherwise, go with AC-Delco Iridiums if it's a daily driver that you occasionally like to spank ricers with. Bnaylor had a list that breaks down the heat ranges of Delco Iridums, and I'm sure he'll chime in when he reads this thread.