K3 visa or immigration?

[akhan]

hello. my husband's on greencard. we got married last year (jan 2008). next year in august he will complete his 5 years as one and will file for citizenship. i wanna know if its better to file for immigration now or wait for him to naturalize first and then try for a K3 visa?
does it make a difference if we file for immigration now or if we file after he naturalizes? any inputs, previous experiences, anything will be helpful.
what is the best option for us?
thanks