if you are a apple type of person and you had teh option between those two phones, get the iphone se. iphone se has wayy better specs the only downside is the small screen and slightly lower battery life. but if you are talking about iphone 6s, they are both basically the same all that matter is if you like big or small screens and battery life (6s has better battery).
BUUTTT if you like android also, i'd highly suggest getting one of the new high tier phones like s8, lg g6, etc. but i think those are overrated. I'd get the OnePlus 3T, great budget phone. I heard its around $400-$500 USD