The Chinese website Chongdiantou has tested a variety of Apple power plugs with the iPhone 14 and the iPhone 14 Pro Max, providing useful data about charging speeds and which is the most valuable for fast charging.
The answer is to use Apple's 30W power adapter, which is the company's lowest-priced option and can charge the iPhone 14 and iPhone 14 Pro Max at their maximum charging speeds of 25W and 27W, respectively. If you want to charge the devices at faster speeds, you should use the new 35W Apple accessory, which comes with dualUSB-C ports.
The chart is in Chinese, but it shows that the iPhone 14 Pro Max was charged at 26W to almost 27W.
While charging speeds for the iPhone 14 Plus and the iPhone 14 Pro remain to be seen, the 30W accessory should be the best choice.
The old 29W power adapter that Apple discontinued in June of last year can be used to temporarily achieve peak charging speeds of nearly 29W for the iPhone 14 Pro Max.
By comparison, the iPhone 13 and iPhone 13 Pro Max are capable of up to 23W and 27W charging speeds, respectively, according to Chongdiantou's sister website ChargerLAB, so lightning charging speeds for all iPhone 14 models are largely the same this year ahead of Apple'
The box with the phones no longer has a power source in it. The company says users can charge the devices to 50% in 30 minutes with a 20W or higher power source.