I switched to a Samsung Galaxy S4 yesterday, after owning 3 generations of iPhones for several years. I've been pleasantly surprised at how much more I like this smart phone than my iPhone.
Better is of course relative, but I've been impressed with the larger and brighter screen, expandable memory options, far better camera (records in HD, and both front and rear cameras can record at the same time) and numerous configuration options.
AT&T also has a $200 iphone trade-in program, which made it an even swap for the 16-GB Samsung! Saved me the time and hassle of placing an ad on craigslist, and paid for the new phone in one shot.
Loving my Samsung. Not missing my iPhone. Lots of new things to learn (and to blog about along the way), but I like what I see so far.