I've read both. They're about different topics. Wizards is about the development of the internet. I found it slightly more fun reading, but both books are highly worthwhile, if you're interested in the history of technology.
but from reading the 'dealers of lightning' it was kind of apparent, that parc had a huge influence on development of internetworking-protocols than is widely known f.e. we must surely remeber about the 'parc universal packet' aka PUP (https://en.wikipedia.org/wiki/PARC_Universal_Packet) as a precursor to the much beloved tcp/ip protocol suite etc etc.
unfortunately, i didn't really enjoy the 'wizards' book as much as i would have really liked...i had the distinct impression that it was kind of 'jumping all over the place'
