Both are different phones, ios is not Android and Android is not ios. So there is basically no comparison. But still I would prefer Oneplus 3t coz iPhone se is very tiny phone and it has underwent alot of price cuts, so the resale value has also went down. IPhone se is also an year or so old device where as Oneplus 3t is Latest. The build quality is very high of Oneplus phones also, don't think that if it's a china company it's bad, the quality is very high. I am myself using Oneplus 3 and used Oneplus 2 and I can assure that no other Android phone can match the experience. Its as simple as that.