I think it varies situation to situation though I think though for most of us, it would be the traffic lane cleaner that gets the most spots and soiling out with out reaching for a specialty spotter or requiring a nuclear rinse.
Three that do that well for me would be O2 prespray.. great for getting the yellow urine spots and general soiling. But still need a pog for heavy tar spots.
Redline plus Oxi.. usually need the citrus for gum and pog for heavy tar/wax. (though haven't tried the new enzyme based formula yet)
Matrix Grandslam.. plus Citrusforce.. Heavy smelling prespray, but takes care of a a lot of spots. Might need a little pog or citrus here and there.
Havn't tried the cobbs powermax.