I am looking for a new laptop, and I found 2 models within my budget of $500 in a local store: one with i3-6006U (dual-core 2Ghz) with iGPU Intel 520, and the other one is powered by A9-9420 (dual-core 3-3.6GHz) with dGPU R7 M440. Both have 4GB DDR4 RAM and 1TB hdd, same screen resolution of 768p. I will use it mainly for office and occasionally light gaming (RPG games, not AAA games). Which one do you think will suit my needs best?
The Intel HD 520 is actually pretty decent for what it is. The dedicated R7 m440 is an entry level GPU that is roughly similar to the nVidia 920m in performance which means it is better than the Intel HD 520. The processing power of the A9-9420 is less than the i3-6006u though. However, for games you generally do want the more powerful GPU (though not by very much) since most games are limited by the GPU.
The recently release AMD Ryzen 5 2500u and Ryzen 7 2700u have the most powerful integrated GPU. The Ryzen 5 2500u has the Radeon Vega 8 integrated GPU and is about equal to a nVidia 940mx while the Radeon Vega 10 in the Ryzen 7 2700u is roughly on par with a nvidia 945m. However, so far the only laptops currently available with these AMD Ryzen CPUs are in the HP Envy X360 series (convertible laptops) with a starting price of $750.