If you ever get to price out a Dell or HP machine with the same features as a Mac, you're ending up paying more than a Mac.
That's partly because Dell does't let you select consumer GPUs for workstations*, and partly obscene pricing for extra RAM, disk and CPU. The last workstation I needed, I was required to buy from Dell (company-forced), and when giving my build order to the IT guy, I complained how expensive Dell is. He replied, don't care, when ordering by phone and mentioning you buy lots from Dell, the price goes down to a rerasonable level.
He was right, the 2500€ shown in Dell's web shop was reduced to 1600€..
* For a development project a few years ago, I needed the GPU to support a specific pixel shader version, and DL-DVI for the 2560x1600 screen. but not much graphics power, and no CAD support. A 100€ entry-level passive-cooling gaming card would have been a good choice, but was not configurable. One only had the choice between close-to-obsolete underpowered CAD cards (150€, not supporting the pixel shader level), and power-hungry CAD cards with noisy fans (800€+).