My Ideal but Practical Mobile Specs (for the year 2016):
Body: Polycarbonate Plastic / Metal body (with inbuilt/external mobile cover having Textured Rubberised Rear Panel)
OS: Android OS, v6 (Marshmallow)
CPU: 1.5/2 GHz 64-bit Octa core
Internal Memory: 3/4 GB RAM & 32/64/128 GB ROM
Memory Slot: MicroSD Slot for Additional/Expandable Memory upto 256 GB / 2 TB
Display: 6/6.5 inch with Full HD i.e. 1080p (1920x1080) / 4k i.e. UHD (3840 × 2160) resolution, Super AMOLED HD / Super AMOLED Plus, Multitouch (2/3/4/5 touch) Touchscreen, Full HD / 4K Video Display & Recording Capability, Corning Gorilla Glass 4/5
Audio: 3.5 mm Jack, Loudspeaker mode, Active Noise Cancellation with Dedicated Mic, FM radio with RDS & Recording capability
SIM Slots: Dual SIM (micro/nano) [both separate SIM slots & not any Hybrid slot], Both SIM supporting 4G (backward compatible with 3G/2G)
Rear Camera: 16/21MP with Flash, Auto Focus, HDR, OIS
Front Camera: 8/13MP with Flash, Auto Focus, HDR, OIS
Battery: 5000/6000mAh Rechargeable with Fast Charging Capability (Qualcomm QuickCharge 3.0 / MediaTek Pump Express 3.0)
Communication: USB 2.0 (480 Mbps) MicroUSB port / USB 3.1 Gen 2 (10 Gbps/SuperSpeed+) USB Type C port (for charging/data transfer), Wifi (802.11n [300 Mbps] / 802.11ac [1.3 Gbps], OTG support, Bluetooth v4/v5, NFC
Navigation: GPS, A-GPS, GLONASS
Sensors (Must): 3-Axis Accelerometer with 3-Axis Gyroscope, Fingerprint, Proximity, Compass/Magnetometer, Light
Sensors (Nice to have): Barometer (Pressure), Thermometer (Heat), Air Humidity, HeartRate Monitor, Pedometer (Dedicated instead of using Accelerometer)