There are some people that seem to know which phone size they want and never look back and others, like me, that just can't decide.
Last year I printed out the little size guides and agonized between the 6 and 6+ for the entire time between the announcement and the time preorders started. Even hours before preorders I wasn't totally sure which phone I wanted, but I finally decided on the 6. It came and I was happy for a couple of weeks, but whenever I was in a store with phones on display I kept looking at the 6+ and wondering if I made a mistake. This was when they were still hard to find in stores, but I happened to find one one day and bought it on a whim. I used it for about a week and absolutely loved the screen size, but not the size or weight of the phone itself. After a week I decided that I made the right choice originally and I returned the 6+.
I was happy going back to my 6... For about three or four months. Then I found myself drooling over the 6+ in stores again wondering if I just hadn't given the 6+ a proper chance. This time availability was better and I ordered a refurb 6+ to save a little money. This time I kept using the. 6+ and definitely enjoying the screen. After about 2 weeks I sold my 6 and stuck with the plus. I still wish it was smaller and lighter sometimes, but this time around I ordered a 6S+ without hesitation.
So, the moral of my story is... Give the 6S+ a chance and you might just decide you like it.