I prefer OEM carts for refilling also. As they start feeding poorly you can use Grandad's purge technique to restore them to excellent function. Last week I scrounged half a dozen empty OEM carts in the cart recycle bin at a CompUSA. The big office supply firms accept some carts and give paper or a credit toward ink purchases, but they generally don't take Canon carts as the refillers don't need Canon OEM carts.
I also have a set of MIS virgin bci-6 carts, two sets of Hobbicolor carts, and some Arrow carts that I use for refilling, and they have functioned well also. Knowing how well the OEM carts work, however, if I were starting over with refilling I would find a way to acquire a few extra sets of empty OEM Canon carts and use them exclusively.
I also have a set of MIS virgin bci-6 carts, two sets of Hobbicolor carts, and some Arrow carts that I use for refilling, and they have functioned well also. Knowing how well the OEM carts work, however, if I were starting over with refilling I would find a way to acquire a few extra sets of empty OEM Canon carts and use them exclusively.