What's the best?

You'll get answers from a range of 2-5 square feet per hen inside the coop and 5-10 square feet outside the coop. I think it's more important that they have more room outside than in, unless you don't have a run. Without a run or free-ranging, I'd definitely say at least 10 s.f. per hen inside the coop. My girls have about 5 s.f. inside the coop, but i've had as little as 3 s.f. per chicken at times. However, since I've recently opened up an addition to their run which is an enclosed "play" area that I open during the day only that has a temporary cage and cover with aviary netting along side their very secure enclosed run, they have about 30 s.f. per hen outside. Since they don't spend much time inside the coop here in North Texas, I make sure they have lots outside. Use to free-range them, but I've lost so many to panthers, bobcats and owls. You also need to allow plenty of room on the roost cuz they squabble over positioning at night. I think the rule there is about 8-12" per linear foot of roost depending on size of your chickens. Mine have more than they'll ever need. Good luck!

gail