Kinda dumb but: Iridium vs Silver?

It might not matter too much performance wise but being the nit pick that I am, I want the very best for my cars. I was debating on wether to get some NGK Iridium spark plugs over some Nology Silver plugs but wasn't sure if I was making the right decision or not. Can anyone help me?

no contest....ngk iridiums:bigthumb:

I agree, they last the longest and will give you the best performance. I loved the set I had in my GTC.