Not sure if anyone did this yes, but I averaged out the case ratings for each game:
Trials and Tribulations - 8.08
Ace Attorney 1 - 7.08
Spirit of Justice (without DLC) - 7
Dual Destinies (with DLC) - 6.77
Investigations 2 - 6.68
Spirit of Justice (with DLC) - 6.5
Dual Destinies (without DLC) - 6.36
Layton - 6.125
Justice For All - 5.8
Investigations 1 - 5.08
Apollo Justice - 4.275
Gave separate rankings for with/without DLC because I feel like people aren't going to consider those cases as strongly when ranking the games as a whole.
Trial and Tribulations is a monster. Its worst case (at a 6.6) is better than half the series averaged out.
Investigations 1 is the only game without a case that scored above 6/10. Truly a consistently underwhelming experience.
Spirit of Justice's average really gets tanked by its DLC.
Layton is propped up by its third case.
lol AA4.