Although I know you prefer smaller phones @pauliunas, I personally would love to see a TRUE 6-inch phone, perhaps with a physical home button, and the power, volume, and photo button on the right side, like a proper Lumia has (had?). Some color would be nice too.
Two of my biggest pet peeves about phones now days are screen size and button placement. Another top is material (metal vs plastic), and a fourth is internal hardware (NFC and Qi charging, camera, etc).
I could go on, but I don't want to turn this into a rant.
I would love to see a dual-boot device too. Then users could get what they really want - choice!