I would recommend using the DNS servers of OpenSRS because:
If your webhost goes down and in case his dns servers are affected as well, mailservers sending to your domain will drop messages as whereas if dns is still up and running and just the server is unreachable the sending servers will queue your message and send it as your mailserver becomes available again (max. 5 days, depends on mailserver implementation at sender site).
From what i know openSRS is a very strong reliable partner beeing the 3rd biggest ICANN registrar at the moment.