Samsung 5660, 5570, 5670 which is the most cost-effective?

I am a freshman girl. I just started Samsung S5560 yesterday. Don't worry, the screen is not as big as you think. Black and white, very nice. Finally, I chose black, which is more durable. The more I watch it, the more I like it. Starting price 1800. The price rebounded slightly. Personally, I feel that 5660 is better than 5670 5570 in all aspects. I think you are also struggling with the shell of 5670. It's hard to find black in the market now.