I'm heavy android user (since HTC Hero, LG Optimus 2x till LG V10).
I tried iphone 5s (last few days), 6 (last a week) & 6s (less than a day), end up failed to keep me wanna use.
But this SE, really something. I can't tell what's the bright side of it, but even with 16gb (people keep saying go for 64gb), it feels good.

Well I've been using some of Iphones series myself for testing purpose, being ended up failed. 5s is the last iphone before SE. Iphone6 last me about a week, which required me to charge during mid day (failed miserably). Same goes for SE, mainly for testing, but SE simply impress me with the battery performance, which last about 2 days per charge. Even for today whole usage from 8am till now another day 1.36am, still got 77% battery. Maybe I less use but it's pretty damn impressive. My G4 already used up 2 full charged 3000mah battery for the same cycle, now using 3rd battery.

Back to your question, the reason stick to SE for the moment is, mine is 16gb, hard to sell when people opt to 64gb. Nonetheless, I use it myself, gambling later on to sell unsealed SE would be much cheaper price. And I know SE won't be able to fulfill my need as a smartphone, might sold it out later. But SE fill me where G4 can't, about 1 handed usage, latest app, smooth transition UI, good camera picture. My other alternative would be Xiaomi Redmi Note 3, or Mi Max, or Huawei Mate 8 for big 4000mah battery last same like 1700mah on SE.