The following result is obtained by our expert's opinion:
Realme 5i
Pros -
• Respectable performance
• Fingerprint sensor
• More memory
• Quad Camera with front camera flash
• Better RAM
• Good design
• Tall 20:9 Display
Cons -
• Less Battery Life
• No fast charging support
• Heavy weight
• No Type C support
Realme C3
Pros -
• Longer battery life
• Better UI
Cons -
• No type C support
• Bad audio output
• Only dual camera
• No fingerprint sensor
Hence, you should go for Realme 5i as compared to Realme C3.