This is one of those open ended questions, your going to get a million answers. So I'll tell you what i've been told from a tech at Jocobs Electronics. The +4 plugs are useless, champion plugs are the worst on the market and autolite plugs are the best on the market.
My advice, use the plugs that your dad used in his cars
I have only used Bosch Platnum over the last 10 yrs and never had a problem. I have had two friends that used splitfire and had nothing but problems.....probably can't go wrong buying OEM plugs from D-C either, JMHO