cheapest option imo is the mid-2012 with 16 GB of RAM. You'll probably need to cop an SSD too.
i dont have a macbook but like you my next hardware gon be it
probably a newer one
a 16 inch maybe in a year or two
Update: copping a mid 2015 15” 16g ram 1Tb tmrw
Bought it today. Ending up getting one with 756g instead of 1TB. Super happy with it!