I bought an Alienware 17 R5, and I am quite pleased with it. I bought a few years ago and it has a GTX 1070, whereas the current ones have the RTX 2000 series.
I was actually hesitant to get a laptop, but I needed something that I could travel with, so after doing research I ended up with the Alienware. From reviews I learned that those with the top graphics card had overheating problems, so that is why I choose the one with the GTX 1070, which would be the RTX 2070 today. If you want more power you can also connect the Alienware Graphics Amplifier, which is said to support up to an RTX 2080 Ti.
For the processor I went with an i7 although an i9 was available, but it would have been much more expensive.
The screen is a 1920x1080 because 4K doesn't really make sense for a 17" screen that is used to do work, but it seems that that option is no longer available.
Hmm, Dell has too many options. I don't see the Alienware 17 R5 anymore, but there is a new Alienware M17 to replace it.
It's a bit late now, but additional specs for mine are 16 GB RAM and 2 drives. Also get Windows 10 Pro.
Presidents day is coming up so there may be some good sales. I got mine for around $2,000.