Depends on the OD on your PF. If he's under 5, just run 3-2 as the safest option. 1-3-1 zone brings your PF outside, and if he has bad OD he'll do no good there and just foul and don't rebound.
I had a game with the 1-3-1 where the C position defended a ton of midrange jumpers from the opposing PG, with a ton of fouls and conceded shots (b/c my C only had 10 OD, vs. 14+ on the other four positions).