In my opinion before buying a smart phone I see its specs according to my use of smartphone.
for best porfomence and gaming snapdragon 650 and above are good .ram should be minimum of 3gb ram. if you are intrested in clicking photos than you should buy a phone with best camera and flash in this you can select phones of oppo, vevo, motorola and etc.
If you are buying an android based os phone than there are lots of choice and you can costomize android phone more than that of ios based phone so all the best for buying a smartphone