The obvious answer is neither.
IT 38 / Smart 10
AB 38 / Smart 10
Crowder 28 / Smart 10 / Brown 10
Amir 24 / Crowder 8 / Kelly 16
Horford 34 / Kelly 14
This except a big NO to Crowder at PF and Smart at SF. Zeller and Jerebko should only be used to eat a few minutes here and there in case of foul trouble or in blow outs. No small ball.
The IT/Bradley/Smart/Crowder/Horford lineup has been fine post-ASB, with a +5.8 net rating. It can stick around as far as I'm concerned. It's not the primary starting lineup's +17.1 rating in that same time period, but it has its place.
That and other small ball line ups only show success do to there heavy usage in end game scenarios where the Celtics are being fouled and I.T. is shooting a million free throws. Those same line ups outside of those end game scenarios are awful. In 37 minutes outside of the 4th qtr. and overtime that line up is -19 points in 37 minutes. In 55 minutes in the 4th qtr. and overtime spanning 25 games that line up is +26 having made 53-57 free throws.
That line ups only usage should be in end game situations where the C's have a lead and even then it would be better to have another big on the floor so they might actually be able to get a stop and rebound.