Oneplus 3 is a budget phone and 6gb ram are very good playing heavy games and oneplus 3 are Dash charging so fast charge for phone and oneplus 3 for may be better than for mi5.
Oneplus 3 is good spification example for 6gb ram, snapdragon 820, Dash charging, and many more features are good and oneplus 3 is camera so good camera sensor OIS clarity are awsome and marshmallow is good for performance.
Oneplus 3 is my opinion is good phone this range price and Amazon for open sale to easly buy and one of best smartphone. but one things may be good and not for design are old phone type but good spification so mobile is awsome.