OpenDNS was the undisputed solution to slow DNS earlier. Though the Level 3 DNS server ( 188.8.131.52) was often better, lack of commitment from Level 3 to keep it available made choosing that option difficult. There has also been rumours of Level 3, shutting down the service.
With the entry of Google DNS, all that has changed. Here is a free service just like OpenDNS but which operates purely by standards and Google DNS is a faster option for many. So which service should you choose? Performance of Google DNS vs OpenDNS varies by country and by type of domains. Here are the results of performance data from 32 countries
|Costa Rica||Tie (Adv. Google)|
|Saudi Arabia||Tie (Adv. OpenDNS)|
|Venezuela||Tie (Adv. Google)|
As you can see Google leads in 17 countries, OpenDNS in 6 countries and 9 countries Tied. You should do your own test, before you adopt any DNS service. Sometimes your ISP's DNS service will be much better than either of these options but the downside is that many ISP's do not care much for security. With attacks against DNS becoming more popular in the recent years it pays to go with a service provider who cares about security.
Even in countries where OpenDNS is faster, it might be better to use Google DNS because OpenDNS breaks DNS standards. If OpenDNS does not find a domain name it redirects the user to a search page, which is an annoyance. This behaviour also breaks some software. Also OpenDNS covertly redirects google searches from some browser toolbars to its own servers. This is without user's consent or knowledge and introduces security and privacy concerns. Since Google DNS operates according to DNS standards, these type of issues do not arise. Google has also promised to not to filter or alter any result.