Hey friend!
I’ve found this thread that has already discussed this at length and I hope it helps you. If you have a more specific question feel free to add that to your thread so people can give you a more direct answer! 
I’ve also found this thread for more advanced Unreal Engine devs that might also interest you.
And finally, a thread talking about laptops for unreal instead of full desktops.
Hope these help and good luck with your shopping!