KF-X Question for you experts

What part of the Korean stealth fighter problem do you guys not believe in and why?

1. Budget (Design/Per Plane ect)
2. AESA Radar (Hardware/Software ect)
3. Engine (Hardware/Software ect)
4. Stealth (RAM/Shaping ect)
5. Airframe (Design/Materials ect)
6. Avionics (Controls/Sensors/Displays ect)
7. Weapons (Missiles and Bombs)
8. Data Link
9. Other

And where do you think the KF-X will be compared to 4.5 Gen fighters and more importantly the F-35,T-50 and J-20?