with that budget you can buy a laptop with pretty much horsepower here are some (I do not think there is different between laptop manufacturer)
They will tailor the laptop to your needs & budget. You can contact them and tell them your budget, the software(s) you will be running, and the things you do (and don't do) with the software (for instance, "I use Solidworks for part modeling and large assemblies, I don't use it for creating photorealistic renders or fea analysis"). They can then create the best system for your needs/budget.
Things that will be important...
Do you work with complex part models and/or large assemblies? Average sizes of files? How large do the files/assemblies get that you work with?
Do you run analysis/simulations/animations?
Do you create photorealistic renders?
Dell Precision Laptops have treated me very well.
I bought a Lenovo closing on two years ago now:
Lenovo ThinkPad W540; Intel Core i7-4900MQ 3.80GHz; Windows 7 64 bit; NVIDIA Quadro K1100M 2GB; 256GB SSD; 16GB RAM
It's only a 15.5" screen, which I chose--quite frankly--just because it's smaller. I don't use it as my main machine--mostly for travel and coffee shop work. I don't do large assemblies, but I do work with complicated parts with extensive feature trees, surfaces, etc.
It performs well, and I haven't had any issues except a screen defect, which Lenovo traded out in 24 hours. Cost $2500 when I bought it.
+1 for the Dell Precision series. You can get an M6800 with the K5100 maxed out on i7 processor speed and RAM within your budget. I only have one complaint about mine.
Not so many choices in laptop storage bags in this large size. I'd like to find one with more padding than the single Targus case I was able to find at Best Buy.
I work in an industrial environment and travel a lot with mine I've put a few dings and bends in the laptop's metal case (especially in the corners) banging it around into machinery and airplanes, but I've been able to tweak most of them out and at least it doesn't crack like my former plastic laptops.