Though a lot of people go for gaming laptops with 1080P resolution, 3K laptops are also gaining high prominence in these days. You are going to have a clear picture as you opt for the 3K laptops. If you are a person who wants a very clear image while playing the games, the laptops with 3K resolution are the most suitable option for you. For driving the 3K laptops, you require GTX 870/880M. 3K happens to be 3 times of the resolution of 1080P. Hence, the graphics processors require working 3 times harder. Hence, you require an expensive gaming device. 1080P is thus a better and affordable option. If you are seeking clear and eye candy, you should pick the laptops with 3K resolution. However, if you prefer FPS over the eye candy, go for the laptops with 1080P.
At the mid-range we see laptops with either the NVIDIA GTX 1060, or for a bit more money, a GTX 1070, both of which are a powerful gaming GPU in a mobile form factor. ASUS offers the Republic of Gamers branding Strix lineup, and the GL504 model is their 15.6-inch range. Featuring the GTX 1060 in the GL504GM, and GTX 1070 in the GL504GS models, there's a wide range of performance here depending on budget. ASUS offers either the Intel Core i5-8300H quad-core, or the Core i7-8750H hex-core CPU, and up to 32 GB of DDR4 RAM support. There's a full range of SSD choices, and you can of course also fit it with a HDD for extra space.
If you're truly serious, and insist on playing all your games at very high detail settings and the highest possible screen resolution (for most laptops, that's 1,920 by 1,080 pixels, assuming you're playing on the laptop's screen and not an external display), you're just going to have to shell out some bucks, especially if you want that laptop to stay game-viable at those settings for more than a couple of years. Future-proofing like that demands top-end graphics silicon: Nvidia's GeForce GTX 1070 or GTX 1080. And that means spending, at current prices, $1,500 or more on your laptop.
The key thing here is to know what you're getting, and to make sure you have the appropriate port free (or that you have Bluetooth support). If you opt for a cabled mouse, don't forget to check the cable length. Is it long enough to reach from a PC tower on the floor to your desk? Is it six feet long, but only needs to run from your mouse pad to the laptop beside it? Also look at the cable itself. A braided nylon or cloth cover is more durable than a standard rubber coating.