Let me have a go.
HW45: better overall build quality, easy to work on, plentiful new spares, 1911 grip frame fits the hand well and takes aftermarket grips, accurate, decent sights and trigger. If you like that kind of thing, easy to disfigure with optics, silencers, and even a wooden shoulder stock. Some have quirky dual power setting (can't myself see the point of that).
Scorpion: OK build quality, bit tricky to take apart and put back together, only old spares though not hard to find, very accurate, weird 70s grip, decent trigger, decent sights until a bit breaks, usually a bit more powerful than the 45 - 5-5.5ft/lbs as against 4.5-5 for the HW (at least the recent 45s I have seen tested). Bit cheaper to buy than a used 45. Early Scorps have no scope grooves, if that matters to you.
Sounds like the 45 is the better all-round bet. Except I have a Scorpion and am very fond of it, and have no great desire to get a 45.
The Scorp is British, iconic, and makes me smile. It shoots really accurately on the rare occasion I get everything right. Whereas the 45 is trying a bit too hard to be a replica cartridge pistol, and not succeeding.
Have you ruled out of consideration the Diana LP5M and LP8?