I think no.3 is the better option, Lenovo Essential G500s Laptop.
3rd Gen i5 for reliablity and consitent performance.
2GB Graph - Dedicated not AMD's shared system memory.
You probably wont need 16GB but its nice to have the option.
Turbo boost is automatic, so you can look at this as a 3.2 GHz but will drain more battery at higher speed.
While AMD are performing better and more superior for desktop gaming now, there laptop cards and no where near as good as a Nvidia. this 2 GB NVIDIA GeForce GT 720M will do a much better job, and there more battery friendly.
Hope this helps
Intel Core i5 2500K /-\ 32Gb 1600mhz RAM /-\ Asus P8Z68/GEN 3
2x 256Gb Crucial M4 /-\ Crossfire XFX HD Radeon 7950 Black DD
Sound blaster Z /-\ yourpcperfect.com /-\ Windows 7 Pro