1.9 imo was a really fun update for experimenting with all of the new arrows and weird effect behaviour that came with them from experiencing it, as well as the combat changes in general. Would say 1.10-1.11 were the best however mainly due to activity (I liked to gank people with death arrows before people knew how to counter them properly), and was new enough to everyone to be balanced in a way due to everyone not using nbt edited totem stacks or complete immortality items at that point in time (which became really common in \~1.14 before they later got super scuffed when you use them now)
Beta 1.7.3 in my opinion since there's no CPS limit, it's super overpowered.
