Best phone under ₹12,000 for my father (6GB/128GB, big battery, good camera, fast charging)

Requirements:

• 6GB RAM / 128GB storage (must)
• Big battery (5000mAh+ preferred)
• Good camera (decent photos, nothing fancy)
• Fast charging support
• Smooth performance for daily use (WhatsApp, YouTube, calls, etc.)
• Clean UI or easy-to-use software (important for older users)

Usage:

• Calls, WhatsApp, YouTube
• Light apps, no gaming
• Needs good battery backup (1–2 days ideally)

I’ve seen options like Redmi, POCO, Realme, etc., but I’m confused which one is actually reliable long-term.Would really appreciate suggestions based on real experience 🙏