From what I have seen on this forum the 309 tends to be a faster grant time. They say that your country of origin has an impact on the processing time but I'm not sure as I am from a "low risk" country, I am from Ireland, I hold an irish and a UK passport. My application is pretty straight forward and we have submitted everything, medical and police checks etc. There has been very little progress and communication regarding my 820 visa application and it has been 26 months since I applied.That gives me some hope that ours will start to move soon. Also from the UK.Some movement for us recently.
Applied - September 2018
Health check - October 2019
Request for police checks - Jan 2020
From the UK, if that makes any difference.
Applied - 1 October 2018
Health Check - April 2019
Request to fill out sponsor application - November 2019 - (didn't do it earlier as we wanted to use it as an easy way to give an update on relationship from October 2018 onwards)