Its a difficult balance.
Scout market purchases come with higher stats out of the box and an SA. They will however decline over the seasons without extra resources.
Young fast training NordGens (or NordGems
) come off the market with lower stats but can improve quickly with extra resources and will maintain that for longer.
Performance will obviously be the key. But one issue is if you can get NordGems cheaply they are more disposable so can be tested and sold if not up to the job, not so easy for Scouts and so you'll find yourself managing their form more.
I've used Scout Market players before and thought of them as Impact Players. My best MC ever was a Scout purchase but lasted only 4 Seasons. I have a NordGem MC atm without SA and he seems equally good and will last longer for no extra cost....or not, who knows.
For me, the changes to the cost, Q and Skill Distribution reduced the advantage of them. I see them as a luxury item but atm its not a luxury I'd go for. For some they might still be considered a good option.
But it really depends where your pitching your team, your ambitions and expectations. It also depends on Token budget.
PS. I've saved a copy of a CL SF match of a team with 4 seasons worth of Scouts in it should I ever need reminding that Scout Market is not the answer to everything.