Before making too many decisions, you need to ping a few DNS servers and see how far they are.
In my case OpenDNS has a server on the rack next to mine at a carrier neutral exchange. The latency difference between my own DNS and theirs is about 1.2ms if I run DNS servers at towers. The difference is less than 1/2 a ms if I run it in the rack.
Every case is different. Google has a router in the same exchange, but it still takes 10ms to get to 8.8.8.8. So I use OpenDNS as primary and 8.8.8.8 as secondary and don't bother with my own anymore.
