4-4,5 inch
1-2GB RAM
Processor - dual core (no quadcore, it is waste of battery)
16GB storage + SD cards
20MPx Pureview camera (Xenon Flash)
HD display (no fullHD, it is waste of battery)
Fancy design (Lumia 930 or iPhone 4/5 - like design)
Battery - as big as possible (at least 4 days of normal...