Full tables will not make much noticeable difference if you are not peering. However you want to make sure both links get used. It can be a 90%/10% split but 100%/0% is bad because then you may discover that the alternate path is actually broken the moment the primary fail. If you choose only default then you need to think about that.
If you join any peering exchanges, full tables will be mandatory. Some parties will export prefixes and then expect a more specific prefix received from your transit to override a part of the space received via the peering.
Regards
Baldur