The steps for choosing the right engine oil blend are based on simple and perhaps not so simple logic. Moreover, your value drivers may add some variation, but here I try to make my thinking apparent so you can evaluate what’s appropriate for your engine and ops.
If you have a Lycoming O320-H2AD or O360E that requires Lycoming’s anti-scuff additive by AD, then consider using an AeroShell oil with TPP (aka TCP); whether straight weight or multiweight depends on the temperature stability of your area or oil change interval. Alternatively, consider using Phillips straight-weight or multiweight oil, and add Lycoming’s additive. The Phillips Victory oil solution will be less expensive, most likely, depending on how you source your oil—at the airport’s FBO, from a local oil company jobber or from a mail-order high-volume retailer, as examples.