Lowest price is your default mechanism for deciding which carrier to use. CLI is rarely the lowest price and may not be a fit if that is process for using a carrier.
More than 2 carriers on your bid list. We want and need to work with companies on a consistent basis to create a shipping process that reduces costs and expands your ability to get product to your customers correctly.
Beating up the carrier to get the best price. Becoming a shipper of preference rarely happens when having carriers compete on price.