spark plugs - too many to choose from.

I'm getting ready to replace the plugs on my 94 Legend and read all the threads pertaining to plug selection. When I looked online at the selection I noticed the E3 DIAMOND FIRE plugs. They are the most expensive of all I found but obviously that doesn't always mean better.
So whats up with these plugs. Are they as good as they say. Anyone on here bought and installed them? Any obvious performance gains or fuel mpg increase. I've only got 115,000 on my Legend so not sure if the age has anything to do with selection.
I looked into the Iridium selection and their about $3 cheaper a piece then the E3's.
Which path should I take here. I'd like to get maximum HP gain and fuel MPG increase or I guess the best balance of the two thats possible.

I CREATED THE POLL FOR FUN MAINLY.