Comparing 64 GB models, the 6s+ is $300 more expensive than the 6p. That's quite a difference for a phone that really isn't better (IMO) than the 6p.
I willingly paid $950 for my iP6s+128, instead of "saving" $300 to get the 6P because:
1. 128Gb>64GB
2. iOS style>Android style (somewhat subjective, but I use both iOS and Android and material design is just awful.
3. iMessage still doesn't have a good Android counterpart
4. Most of my friends have iPhones so it makes life easier
5. Apple doesn't abandon their phones as quickly as Android manufacturers do.
6. Ease of repair - just to go Apple store, and I will walk out with a working phone, one way or another.
7. Superior microphone on the 6s+, callers on the other end can hear me more clearly, makes phone conversations nicer
8. OLED is the devil, and God help us if Apple ever goes that route. I can leave LCD on forever without burnin.
9. The wallet case I use is only available for iPhone. Tons of accessories are only available for iPhone.
Reasons Android/Nexus better than iOS:
1. iOS notification bar SUCKS compared to android and always has.
2. No notification LED, which is why I have to leave my screen on 24/7 unless in my pocket and sound turned on.