Citizenship by Descent or Right of Abode?

Hi, I'm looking to move to the UK to live and work. Already have a job offer and they want me to start ASAP - so in good shape there. Now onto my question.

I'm was born in NZ and am currently living in the US, but my mother was born in the UK and emigrated to NZ in the 50's. I believe I'm entitled to citizenship by descent. I also believe I'm entitled to right of abode. Which is the best and quickest route to go down. I know that citizenship is probably the best end game, but its how long does this process take that worries me, and is right of abode just simply easier and faster?

Many thanks.

When were you born?

..hi there. 4th of Feb 1971.

You are not yet British.

However, I think you may apply for a CoE-RoA (2(1)(b), 2(1)(d)).

ROA4 Basis of a person’s claim to right of abode wrote:5. A Commonwealth citizen (not a CUKC) with a parent / adoptive parent who, at the time of the person’s birth / adoption, was a CUKC by birth in the United Kingdom

Applicant is a Commonwealth (not British) citizen born before 1st January 1983 to a parent who was born in the United Kingdom wrote:Additional documents which must accompany an application for a certificate of entitlement

(i)Applicant’s full birth certificate showing parents’ details; and
(ii)Parent’s full UK birth certificate