Hey Op, newer would be the logic answer if we don't take into account your budget. So first of all, if you can wait two more months and get an iPhone 14 for a cheaper price, I think that would be a master move. Some people will tell you that everything on the iPhone 14 is the same as the 13, from the screen to the CPU, but they aren't taking into account the extra 2GB of RAM the iPhone 14 has, and if you want to future-proof your purchase, my guess is that a phone with 6GB of RAM will hold much better than one with 4GB. Maybe not now, but it will start to become noticeable in the future, and the 14 will probably get longer iOS support than the 13 despite sharing the same A15 SoC.
At the same time, on September, the iPhone 13 price will drop, probably to the current price of the iPhone 12, so if your budget is tight, that could be a good option as well. The iPhone 12 will probably get discontinued in two months. Also the A15 devices have better battery life, especially if you turn on the low battery mode often, and the A15 chip will probably be one of the best supported by Apple and developers, because there are a ton of devices using it: the latest Apple TV, the new iPad mini, the iPhone 13, 13 Pro and the iPhone 14…
Those would be my two first options, if I were you. Wait until September and get either the 14 or the 13 depending on how much you're willing to spend.
However, let's say that you cannot wait until September, or you have seen the iPhone 11Pro and the 12 at a very discounted price and your budget is really tight. The iPhone 12 could be a good purchase if the price is very good (that’s why I selected it), however, keep in mind that the iPhone 13 lineup starts at 128GB of storage, and the iPhone 12 starts at 64GB, a storage that nowadays or in the near future can become too small.
Definitely don’t buy the iPhone 11 Pro new, especially if you want your new device to have many years of iOS support and you want to enjoy the latest features based on the Neural Engine. The A13 is a great SoC mind you, but it is the least power efficient of the 3 we’re talking here, and it has half the cores on the Neural Engine than the A14 (iPhone 12) or the A15 (iPhone 13 and 14).
I hope this explanation is useful for you and everyone else wondering what iPhone to buy! If you have more questions don’t hesitate to ask.