It always depends on the speed you wish to sell of course
If you need them gone as soon as possible then lots will be the fastest but if you have more time you should list them individually. G3s can take some time to sell but normally they will move eventually. While you save on fees via the Arena, you are more likely to sell and make a little more if you try ebay.
The majority of common G3s run around the $3-5 mark but some do better than this of course. You can take a guide price by completed auctions on ebay or even ask for pcs in batches here in the Corral