The first question I had on my journey to relearning Koine Greek was which pronunciation to use? In terms of Koine Greek the two most popular today are Erasmian and modern. When I first took Greek almost eighteen years ago Erasmian was by far the most common. Almost every resource and text book used Erasmian. Today I am starting to see more resources available using modern pronunciation. So this go around I have a choice.
This time I choose modern for two reasons.
The first being the parish I am priest at is dedicated to St. Nectarios and my wife and I would love to do a pilgrimage to Agenia. So with that in mind already knowing modern Greek pronunciation puts me up a bit when I go to learn some conversational Greek.
The second being I have some friends that are Greek speakers so if I need to get some help learning they certainly will be using modern pronunciation.
My choice was based strictly personal reasonings. Your choice may be different.