Hands-down, the iPhoneSE.
I bought the original iPhone for my wife when it was first announced all those years ago. It was nice, but the iPhone4 was nicer. So, when the 4 came out, we both got 4's. When we decided our son needed an emergency phone, we gave him one of the 4s, and traded the other for an iPhone5. As Apps became more demanding, we offloaded the iPhone5 to our son and sold his 4 on eBay, replacing the 5 with an SE. Then I replaced my 5 with an SE after laundering (yes, washer and dryer) the 5. From then on, the SE met every requirement we had in a smart phone. The size was perfect for a purse or pocket, it didn't bend, it was fast enough, and worked well enough as a phone. I just recently went to an iPhone7 due to a battery replacement gone bad in my SE. TouchID/Home Button cable separation. A very sad day. As nice as the iPhone7 is, it feels clunky, almost too big to use as a regular phone, and you can't pick it up without getting fingerprints all over it. The design of the iPhoneSE needs to be revisited, perhaps with an iPhoneSE2. Some people prefer a phone to be a phone that just pairs well with other devices, has good signal reception, good battery life, with a bend-proof, scratch-proof, water-resistant enclosure. If we need to see something faster, bigger or more clearly, we have iPads or Macs for that. Just sayin'.