If you are already an iPhone user and have extra money now, upgrade to 7 Plus.
But, if you are not willing to spend too much now. Next year, iPhone 8 will be a major and game changer worthy upgrade, as that will be iPhone 10th Anniversary, so Apple will have something groundbreaking for that, as you can already see the rumor mills.
The major problem which made me return my 7 Plus the next day were those slight hissing sounds present in minority of iPhone 7 series. I noticed them first in video recording, as those sounds were causing very minor sound distortions too.
The major problem i face with iOS is too many software restrictions, but still i keep iPhones as one of my phones to explore them thoroughly.