MOLLE hands down. Every rig I have is MOLLE and I can swap out pouches as I need to. Yes, it is a bit more of a pain to install them, but in the end it will save you money as you can get the base vest you want and outfit EXACTLY how you want. If you go from a plate carrier to a chestrig, just move pouches back and forth.
Even though the panel option is a cheaper "alternative", in the end you'll probably end up going MOLLE anyways. There are lots of cheap options out there for MOLLE vests which are clones of popular makes and models for less than half the price of the original. I have a Wasatch clone which cost me around $225 to outfit with Hyd pack, and various other pouches. A real HSGI Wasatch would have cost me $500+ for essentially (in airsoft terms here) the same thing.
I think clones are the wave of the future. I mean think about it. How ridiculous is it to spend $500 on a "toy" gun and then another $500-600 on a rig to carry your $10 mags? We use replica guns, we have replica camo, we might as well use replica gear. Only makes sense.
Age verifier Northern Alberta
Democracy is two wolves and a sheep discussing what's for dinner.
Freedom is the wolves limping away while the sheep reloads.
Never confuse freedom with democracy.