I find the plate carrier to have a more rigid feel so the pouches are solid on the rig vs. a vest which has more give.
Plate carriers are very hot though, come summer time you're cooking with one on. I find vests are nice when it gets really warm.
Right now I'm running a soft plate carrier with a Ferro tactical rig on top of it. Or I can run the Ferro rig on it's own.
Airsoft, where nothing is hurt but feelings.