The best options under/around $600 are gaming laptops with a the Radeon M385X (only the Lenovo Y700 AMD) and laptops with GT 940M (and sometimes GTX 950M) and an 1080p screen, currently. The 1080p screen is a big plus compared to past laptops under $600 and you should look for it. This kind of performance is adequate for low-midrange graphics settings.
If you are willing to go refurbished and up to $650-$660, you can get yourself a nice Dell 7559 with GTX 960M, IPS, I5-6300HQ and an IPS, which will be much faster than the Y700 in DX11 and will have less problems because the Intel+NV ecosystem and manufacturer support are currently better.
Frankly, there was not a lot of change in gaming performance in this price range in the last year or year and a half and besides some deals here and there. Some aspects were improved, like display quality, in some laptops.
For now, I’d go with the 7559 for $650-$660 and with the Y700 for $550-$600.
- [Refurbished] Dell Inspiron 7559, for $650-$750 15.6″: I5-6300HQ (4C/4T), GTX 960M 4GB, 1080p IPS display and 1TB SSHD/256GB SSD. Easily the fastest under $650 if you are willing to spend that much and go refurbished (which includes official Dell warranty). The 7559 lately became available refurbished via Dell Home Outlet, eBay and others. I think this is a good purchase if you are interested mostly in gaming performance. The IPS display is nice but not great and lacking some color, speakers and keyboard can be described as mediocre. Thermals are pretty ok and gaming performance for $650 is the highest you can get.
- HP Pavilion 15 (15.6″) : With a default 1080p IPS display, Skylake I5-6300HQ CPU and GTX 950M DDR3 or GTX 960M GPU. The 950M version costs around $600 with coupon (and you have to add tax) and the 960M costs around $680-$700 with coupons. Check coupons
- Acer E 15 E5-575G (15.6″), around $600, GTX 950M 4GB, the new Kaby Lake I5-7200U CPU, 256GB SSD, 8GB DDR4 RAM, 1080p display (probably not an IPS). Should be a nice laptop for $600. I’d wait for the new models
- The new Acer E5-575G 15.6″ via Amazon (link) or Newegg (link, HDD, not SSD) for $550. New Acer’s budget gaming laptop, upgraded from previous models with a GT 940MX GPU (GDDR5), 256GB SSD, I5-6200U CPU and 1080p display (TN). It also includes a USB 3.1 type-C port (3.1 gen1). In comparison to the GT 940M competitors, the 940MX GDDR5 performs considerably faster for gaming, up to 50% faster than a 940M.
- The other recommendations are currently the same as the $500 laptops recommendations – please check.
For heavy gamers, I would recommend saving some more money or wait for good refurbished deals.
For higher performance, I suggest checking the 600$-800$ gaming laptops recommendations. The $800 up to $1000-$1100 gaming laptops are usually much more cost effective in terms in gaming performance (like screen quality) and general value you get for your money.