I have been using Sony Xperia android phones for a long time now. They are one of the few that told microsoft to shove it with their patent extortion, and their top-spec hardware is generally capable of being unlocked and romable with xda love.
Currently using a Z5 Compact, haven't unlocked it to maintain security updates, and not too annoying not having root. Prior I had a Z1 Compact, and a number of the Xperia Mini phones that were all bl-unlocked and rommed. I always prefer a small phone, the original mini's were 3" androids, and still my favorite phones. I have to settle for a large 4.6" in the "compacts" now for modern hardware, but they're pretty nice, and the bigger cousins for the giant phone crowds just have better displays. They usually do a 5.2" and a mega 6".
Only good reason to upgrade beyond a Z3 was the fingerprint reader, but Z5 is nice with it for a convenient security mechanism for using it. The current X Compact and XA bigger 5.2" were selling for less than 300 dollars around black friday, deals can be had.