There was a time that I practiced both the zone and press and didn't always run the press. But since I reached the prestige I'm at now, I always run press. What I meant is I always run press/zone, but gameplan whether I run 3-2 vs 2-3. Since my SF is a stud, I pretty much always run 3-2 unless the team I'm playing plays PF-PF-C or PF-C-C in their front court or they are just a fantastic rebounding team.
One other thing... most look at how well the other team shoots from the perimeter vs the post to decide whether to go 3-2 vs 2-3. I use +/- to combat that. In deciding 2-3 vs 3-2, I think rebounding is number 1. Then I look at how well the PG can pass the ball. If he's 90+, I'm more likely to go 2-3 and vice-versa.
Finally, if you've got tremendous shot-blockers at PF and C like I do, then you'll see why I love 3-2. Especially if the other PG has a high BH rating. Let him penetrate, then swat! :)