Tried running a chest rig (OE TECH OPS), but I can't stand having my gear that high up, so it's a no for plate carriers too. I want to be able to reach my pistol and left side dump/utility pouch with ease, while being able to prone comfortably. If I ever somehow needed to run an actual one, I wouldn't like to make use of the molle space honestly. Maybe for low profile pouches like admin pouches, but that's it. Belt rigs so far work the best for me.
Currently, I'm running a OE Tech Crossover leg rig on top of a regular leather belt. Double M4 stacker pouch (open top) is stuck at my 10 o'clock, with one strap running through the other side to keep it from jiggling around. Holster sits at the opposite side (roughly 3'oclock), paddle, and locks onto the belt and belt snugly though I would prefer direct belt for security; alas, I need something better than a carabiner to hold down that other end. The other end of the leg rig's pouch is kept in place by a carabiner clipped to an adjacent belt loop. If I could, I would have ITW FAST mag style holders at my 10 o'clock, and the dualie M4 pouch at my right side in front of my holster (ITW FAST for the reload process, dualie mainly storage [I'd move up magazines as I go])
The only thing I'd consider apart from it is are side plate molle panels, since I can find a use for the region between 100 to 150 degrees from my front (underhand grab bb bottles, magazines via FAST carriers, etc.)