what are the CLoudflare.com BASIC (free) service downtimes in the past months, years?

I know my server uptime, but not CF uptime on BASIC service.

So question is if i get more uptime when i point domain to my server nameserver or cloudflare nameservers ?

On my domains, there are backlinks that must retain, if are down for more than 36 hours, they are irreversibly removed by the backlink selling system.

Im not sure if i can guarantee 36 hours replacement if my server die, so maybe better to point domain to CF nameservers...