Want to save money on a fancy new phone? In the long run, it makes sense to buy the phone upfront. Sure, you'll pay more immediately, but your monthly costs will be less because you aren't paying the phone off month to month.
You have to buy an unlocked phone, though: one that is not locked to any particular phone network. Like, say, these great deals from Amazon on the unlocked Samsung Galaxy S21, where this top-of-the-line phone is up to 20% off.