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 220.127.116.11 or 18.104.22.168 … 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.