Perhaps an unpopular take, but I think they're both one dimensional and overrated.
I agree, but IMO Pacino's schtick is entertaining. De Niro's is wooden. At least Pacino has a coke-fueled energy to him instead of a brooding wannabe tough guy bully like De Niro. That works in roles like Heat, but falls flat in other moves; Pacino's high energy in contrast.