I've tried various options over the years.
Had 2 different parrot kits (ck3100 and the 3200 colour) both were 'ok' but sound quality for people on the other end of the line was rubbish!
Then I tried the Alpine bluetooth adaptor thingy to connect with my headunit, and that was just pathetic and unusable (common issue, although they are rumoured to have sorted it for the newer models)
At the moment I have a Bury cc9060 (the touchscreen one). This has been AMAZING compared to the others, would definitely recommend it.
I have no experience with bluetooth headunits, although I've heard the only downfall can be lack of external microphone hindering call quality, but can't comment from personal experience.
Would definitely recommend the Bury, top piece of kit, has voice activation for menus and can read out text messages to you as well!!!
Andy