I was a forever user of iPhone and the 3.5-4" screen. I did like it at the time time, but after having many many devices over the last couple years. The Moto X is probably the most comfortable device I had ever used.
That said, I have had the LG Optimus G Pro (5.5"), the Note 3 (5.7"), and now I have both the LG G2 at 5.2" and the Nokia 1520 6" (running 8.1 and its awesome).
The LG G2 at 5.2" and the with no buttons on the side, I now think it might be THE perfect phone. I can use it one handed with no issues.
The Nokia 1520 is media consumption, is amazing. I was going to mess with the Nokia for 14 days and return it. Now I might sell my G2 and keep it.
I thought it would just simply be Too big, but after getting used to it, I think I am in love with it. (never thought I would say that about a WP hah)
I work for apple, so I still handle iPhones ever single day. I miss iOS and the syncing abilities of iCloud and my iMac, but I don't miss the screen size.
If iPhone 6 aligns with the 4.7" rumor, I will more than likely switch back to iOS for a while. After having android and now Windows phone, I don't think I will ever just stick with one phone, one OS ever again. I love switching phones about every 3-6 months.
I love iOS and iPhone, but I love android and Windows Phone 8.1. The only phone I haven't tried, that I want to try, is the Blackberry Z10/Z30.
I just am starting to kind of hate samsung because of touchwiz, and I don't root phones.