Spark plug differences...need help

I keep hearing Bosch Platinum spark plugs suck in our blazer...I want to know...
1. ) Why they are bad?
2. ) What will be the difference if I go to something such as AC Delco Platinum
3. ) Is it worth changing them out now?

I've warned you too many times about this. Why can't you use one of your other threads? You constantly start threads, let people answer, and then come back a week later and ask the same question again. You started 4 threads asking which brake pads were the best despite constant warnings, and now this makes 3 threads asking about the difference between Bosch and AC Delco. All of your threads have received multiple answers, but you continue to start new threads asking the same questions again.

I'm going to give you a couple weeks to browse the forum and learn the proper way to do things.