There's no 'right' answer. It depends a lot on your lifestyle and motivation. Basal bolus or MDI is the most flexible, but means more injections. If you have a very predictable life and happy to eat same meals and snacks at set times and prefer to avoid mulitple injections, then premix/biphasic may work well for you. Also it helps if you rarely need to change your dose! Whereas if you have a more variable lifestyle, you may prefer a more flexible but higher-maintenance MDI approach.
With premixed insulins the proportion of short- to long-acting insulin is fixed, so its less easy to fine-tune your dose unless you also have some separate fast-acting available. Some people need frequent dose changes, others less so.