In my experience, and living in a lightning-rich country, Panamax has given me the best results so far.
I too installed a whole-house protector (Primax), and have protectors on ALL incoming lines: coax, data, telephone and power.

Aside from that, at my HT location I installed a MAX-5500 EX, which has a very nice isolation transformer in addition to the normal surge protection. Coax, data and telephone lines go thru the 5500 as well in that location, so there they have double protection.

I have never had any sort of problem with any of my connected equipment, but still Panamax offers an excellent replacement guarantee for all connected gear, plus a lifetime warranty for the protectors themselves. They will be replaced at any authorized dealer, no questions asked, for as long as you own the product.