First of all... most important 2 things that you should look first are COOLING SYSTEM and MATERIAL from which is laptop built and after those 2 things then watch components, keyboard, screen etc...
I bought ASUS ROG STRIX SCAR 2 (115W rtx 2070/i7 etc...) and this bad boy was overheating rly rly much... (CPU goes up to 90 and GPU up to 80) HP/LENOVO goes even up to 95/98 for GPU) - its not a big deal because laptops are designed to withstand much higher temps then desktops but anyway, why risk it when you can simply avoid it right? (I fixed it with undervolting both GPU/CPU, repasting, cleaning from dust etc)
- Wait for new ASUS 2020 Series of gaming notebook!!!!!! WHY?
- Because ALL NEW models are using THERMAL GRIZZLY's Liquid metal thermal compound condoctonaut which is lovering CPU/GPU temps way to far (up to 15 degrees)
Long story short
THINGS TO WATCH (from more important to "less" important) - thats just my opinion
- Cooling system (95% manufacturers are using low quality thermal paste because that dont wanna have big money loss during production) - ASUS is the first one that now in 2020 have rly good thermal design (mostly cuz of the liquid metal) btw HP omen used liquid metal before ASUS but it wasnt that good like ASUS did in new series...
- Build quality
- Components (CPU/GPU/RAM/SSD (RAID 0)/DISPLAY (Refresh rate/response time/panel type/keyboard etc...)
- Battery life (depands from user to user... btw ASUS ROG 2020 series has rly nice 90Wh battery)
Overall, you maybe think that i am asus fanboy but man, i had way to much problems with mine ASUS ROG GL704GW especially with OVERHEATING and i dont want you to have same problems that i had... Just imagine playing games and u quickly check temps and its like 90... - u cant even focus on the game cuz laptop is overheating and u are like "omg, will something happen to him because it is so hot?"...