Hi,
There's no "better". Banana plugs are simply more convenient, easier to connect and disconnect than bare cable, and it's less likely that a strand of the cable would fray and short the connection between the speaker connections.
Both methods use a contact connection, which is entirely adequate to transfer the high-level signal from the cable to the speaker posts.
Regards,
Alan
Certainly banana plugs are the most convenient, however, I would caution that if your preference is a heavier duty thicker speaker cable, because of the cables extra weight and stiffness, it can actually break off the connection quite easily in which case it would be better to go to a direct wire or spade connection.
