I start with some spec's then people will kick in and tell you why I am wrong.
Get a good size screen 15"+ (screen dimensions are measured on the diagonal)
Get a I7 chip, less cores more speed imo, most will be quad core anyway now-a-days. I'd take a twin core at 4ghz+ over a quad core at 2.3ghz+ myself. (don't get anything that says O/c - over clocked)
Get a lot of storage memory/large hard drive, its the driving reason for the unit, 1tb minimum.
I'd prefer a separate video card as it takes up less resources from the laptop.
Don't worry about software apart from a legit version of Windows.
If you have someone who reconditions ex-govie stuff, reviews well and offers a warranty I'd consider them quite high on my list.
Steve
Ps. Gumtree is great for 2nd hand lap's, -
https://www.gumtree.com.au/s-ad/nort...top/1304320596
While I'm not recommending that particular laptop, it is a benchmark if nothing else, see point 6.