IPhone 5

iPhone 5 was the last iPhone tested by Steve Jobs, and was the first iPhone launched under Tim Cook's administration. This iPhone kept the classic iPhone 4 stainless steel border, but also introduced more visible attena bands to the back of the phone. The iPhone also had a bigger display, while keeping its reachability.

This became the first iPhone to reach 1,000 mb (or 1 GB) of RAM and introduce the A6 chip.

Sources:

https://www.cultofmac.com/310378/speaker-test-ranks-every-iphone-model-order-loudness/

https://en.wikipedia.org/wiki/IPhone_5