Which iPhone 12 series should i buy

Mobile model selection is an individual choice based on many parameters. Such as Money, Feature, Status, Aesthetic, Utility, User-Friendliness, Availability, Warranty Coverage, Service Support, Resale value, Technology, and many other factors.

You can choose yours, based on your need. Go through tech spec of all iPhone models in one place, here --> iPhone Tech Specs - Apple Support And iPhone - Shopping Help - Apple

the one that suits your needs and that you can afford

iPhone - Compare Models - Apple