Unless your ISP's DNS is Fubar, I'd suggest it makes little to no difference to almost every user on the internet.
I sit here .. type a domain into my browser .. takes 3 seconds ....
I hit enter .... 100 microseconds ...
My DNS request is sent .. 10microseconds ...
My ISP's DNS resolves it ... 10microseconds .. Or my ISP sends the request to higher tier DNS ... 20microseconds ... or sends to a higher tier DNS 40 microseconds
My PC sends a request to access a webpage ... 10 microseconds
The extremely over-utilised webpage server negotiates connection & starts uploading my page .... 10microseconds
Webpage Server uploads 1MB page at 100Kb/s per second regardless of your connection .... 10 seconds.
DNS resolution time ....
Time to type URL & hit enter -> 3.100 seconds
Time to resolve DNS using your ISP -> 0.040 seconds.
Time to send hundreds of file requests & receive complete Web page & images -> 10.000 seconds.
Time to make coffee while you're waiting -> 120.00 seconds.
Loading 200MB Youtube video -> 60 seconds ....
Total = 13.14 seconds
DNS resolution ... 0.04 seconds ...
Total percentage of time resolving DNS: 0.3%
I can imagine that shaving a few microseconds off your DNS resolution makes a world of difference to every user in the world .. it's like night and day ... OMFG!
IMO, unless your ISP's DNS is useless because they're filtering sites, or is incredibly unreliable, or <insert very good reason which is not "because I can" here>, there is no valid reason to change your DNS to another server, unless you are a google-zombie and desperately want google to know where you're going today.
If you were feeling particularly google-zombie like, but aren't a full-time google-zombine, I guess you could set your secondary DNS to googles 126.96.36.199 or 188.8.131.52 .. just in case your ISP's DNS dies a horrible death.
I think that in the last 3 years, my ISP managed to have a DNS go down for about 5 minutes while they performed scheduled maintenance sometime between midnight and 1am.