The Martens system
A modern bidding system should have the same structure as a tree, with its roots deeply established and its limbs flying out to the sky. All its juices pass from the earth to the crown, with the leaves grabbing the light and passing the energy of the sun to the trunk and roots.
In the 21st century, many bidding systems look for a symbiosis between relay bidding and a two-way exchange of information. Specific consideration must also be given to camouflage, wherever this is possible without obstructing the quality of the final contract.
I believe strongly that a pair should use different systems, depending on the vulnerability.