The Dell G series laptops are Dell's answer to gaming laptops. The most popular one is the Dell G16, which has budget models starting from over £1,000.
Generally speaking, even the slightly older G15 model is still great for gaming. Even the budget options have respectable specs that still perform well when running most games. The more premium G15 laptops can be purchased with the latest processors and dedicated GPUs, which do well running basically every game.
The faults people find with the G15 (that are present in most gaming laptops) are that it's a bit loud and the battery life isn't amazing. Some models also have panels with slow response times so ghosting may be a huge issue if you're playing games that demand quick reactions.
The Alienware x15 is also worth mentioning here. Alienware was acquired by Dell so they technically are Dell laptops. More importantly, they're one of the most recognized gaming laptop brands.
Since they're built with only gaming in mind, they do make for a better experience. Fast screens, quick processors, the latest mobile GPUs -- basically the whole package.
Their design makes them divisive among users though. Compared to the Dell G15, for instance, it's much more futuristic and bulky. If you'd like a sleeker laptop that won't stick out or break your back carrying it around, you should probably still go for the Dell G Series.