Here is how to install namebench - perl script that will find closest public DNS providers with fastest average response time.

git clone https://github.com/catap/namebench.git
cd namebench
./namebench.py

In my case namebench told me:

Mean response (in milliseconds):
--------------------------------
OpenDNS ####### 139.50
DynGuide ####### 147.79
NTT ####### 148.15
Genuity (2) ####### 148.47
Google Public DN ####### 150.35
Hurricane Electr ######### 186.82
Sprintlink ########## 207.67
UltraDNS (2) ########### 234.90
GlobalSat ################################################## ### 1186.03

Recommended configuration (fastest + nearest):
----------------------------------------------
nameserver 208.67.220.220 # OpenDNS
nameserver 129.250.35.250 # NTT
nameserver 216.146.35.35 # DynGuide
before using any DNS IP in /etc/resolv.conf file, Google: DNSIPHERE reviews privacy

namebench configuration (number of threads, timeouts..):
vi ./config/namebench.cfg