Arguing 'better' teams from dramatically different eras is always tough._lefraud_ said:
All Time better than 2018:
1964
1969
1975
1976
1980
2007
2016
As for teams that were arguably better (or at least equal):
2006
2008
2010
2018
Technically if you put the 2018 team in a time machine and put them back in 1964, they'd probably wax that team. The physical conditioning programs/nutrition/athleticism of players today is so much more advanced than back then. Just flat out bigger/faster/stronger players now in general. Not to mention totally different rules and game (including the 3-point shot). Doesn't seem like you can objectively compare two teams that played 50 years apart.