7-inch tablet computer recommendation

If your budget is limited (no more than RMB 2,000), you have the following options:

Google Nexus 7: Quad-core processor, 1G memory, front camera, 8G, no expansion card, Android 4.1, wifi
Samsung P3110: dual-core processor, 1G memory, dual cameras, 8G, expansion card, Android 4.0, wifi
Kindle Fire: dual-core processor, 512M memory, no camera, 4G, no expansion card, Android 2.3, wifi
Acer Iconia Tab A100: dual-core processor, 1G memory, dual cameras, 16G, expansion card, Android 3.2, wifi
HTC Flyer: single-core processor 1.5G, memory 1G, dual cameras, 32G, expansion card, Android 2.3, wifi+3G
Lenovo LePad A2107: single-core processor, 1G memory, dual cameras, 16G, expansion card, Android 4.0, wifi+3G

In terms of price, Google Nexus 7 and Samsung P3110 are around 1,700, while Kindle Fire and A2107 are around 1,300. In terms of cost performance, A2107 is much more affordable, but the quality of domestic products is not very reassuring (although Lenovo has no problems), and I prefer Samsung P3110.