Nobody is imitating Pacino tho. Brando's role is like Pacino in Scarface.
I know this post is 4 years old but ima respond anyway. Brando was very operatic in his performance, so was Pacino in Scarface - that lends itself to imitation. This is like saying "well 'If I Ruled the World' is catchier than 'Memory Lane' so therefore >>". Nah they're both excellent performances but in different lanes.
Pacino's genius was in his subtlety, his response to Moe Greene is the perfect example.
"You straightened my brother out"
He doesn't ask a question, nor does he scream it - he just states it very plainly but what he's really saying is "you're a dead man".
Or when he finally walks up to Rocco, "You have to answer for Santino..".
There's nothing exciting about re-enacting that, but it's just so chillingly brilliantly acted because he's borderline boring but he toes the line so well that he adds an entire dimension to it.
Which is exactly why the studio didn't want him, they thought he was boring and didn't see it until Coppolo showed them the scene where he kills the cop and Solozzo.
Caan/Garcia acted with anger, Brando/Deniro acted with warmth, Cazale acted with fear, Pacino acts with