OK, I'll throw in my $0.02, since I've had at least two silver vehicles (often five or more) for over twenty years.
Haven't tried EX or Zaino..so I guess I can't say my choice is *best*. And there's a huge eye-of-the-beholder factor here; I, for instance, just don't like how KSG looks on silver (though I use it on the beaters).
I've tried a lot of stuff (other than the PB's and Zaino) including many of the combos listed here (and various Pinnacle, Autoglym, and other combos); nothing I've tried comes close to 1Z PP/MP topped with UPP (formerly Platinum). Side-by-side comparisons with the same silver paint using other products are just remarkable; you'd swear it was a different paint. The 1Z/UPP gives surprising depth for a synthetic and the metallic is just dazzling. Literally blinding in bright sunlight, but not at all "plasticy". But I give a lot of credit to the prep- working the paint until it's as good as possible still counts for 95% of it, even on silver. Still, adding the UPP really made a big difference for the better.