K3 visa/immigrant visa/immediate relative?

[NZAli]

Hi there. My boyfriend is American and I live in New Zealand, where we will marry in a few months. From the information I have found on the internet it seems our best options are to apply for a K3 visa for me (as a spouse) after we're married, an immigrant visa or an immediate relative visa. We're anxious to file the correct application. It looks like we can see the American Consulate in my city after we're married and file the documentation there. The length of time from application through to processing and acceptance seems to vary (from information on the internet) from 6-18 months. Does anyone know which is the correct visa to apply for? And secondly what an estimate of time is before my application is approved. Many thanks.

[able1]

See-- http://www.worldlawdirect.com/article/796 and http://www.worldlawdirect.com/article.php?id=1903