Beds vote from me.
I normally would do 3-7gallon pots to flower in, but recently used a 45gallon geopot "bed" to flower my 16 seedlings in, I did veg a couple weeks so no 12/12 but that shouldn't be much different.
I ended up with 8 females after cutting out males and a runt or two.
This is only under 250w of COB leds, I think these are the biggest plants I have had under that small of wattage. they would have been smaller in 5 gallons pots and no way would I be able to fit 8 let alone 16 in my small tent.