Google Public DNS opened few days before and Open DNS was there, your ISP DNS will be there and there are many others too. now are you confused which one will be the best option for you?
here are some Utilities that will help you to find the best choice for you.
1. GRC Domain Name Speed Benchmark
You can add or remove the Domain Name Servers. Sort in the order of the speed. Can check the Cached, Uncached speeds separately etc.
GRC's DNS Benchmark performs a detailed analysis and comparison of the operational performance and reliability of any set of up to 200 DNS nameservers (sometimes also called resolvers) at once.
Once the benchmark finishes, the results are heuristically and statistically analyzed to present a comprehensive yet simplified and understandable English-language summary of all important findings and conclusions. Based upon these results, users may choose to change the usage order of their system's own resolvers, or, if alternative public nameservers offer superior performance compared with the nameservers currently being used, to switch to one or more alternative nameservers.
2. Namebench
Namebench runs on Mac OS X, Windows, and UNIX, and is available with a graphical user interface as well as a command-line interface.
Namebench runs a fair and thorough benchmark using your web browser history, tcpdump output, or standardized datasets in order to provide an individualized recommendation. namebench is completely free and does not modify your system in any way
3. Dns Tester
You can compare two DNS ips here to see which is faster. you need to enter them manually.