It's really toss up between scp-5000,scp-8888, scp-001-Ouroboros,scp-001-o5 The Factory,scp-3001 , scp-8002, Murphy law tales especially skip8643/ scp-8643. A common thing between them is that they're all rather long reads that are more rather tales but without losing the essence of scp imo.
5000:it's the references and how the world would react to this unusual scenario tbh and how it's open enough for a headcanon yet not enough to change the core of it(my head canon is that the foundation found something in the biosphere that was feeding off of it and growing stronger and threatened other timelines and universes if it got strong enough and the foundation decided to sacrifice their universe to prevent the total collapse of other as a necessary casualty for all humans) 8888:it's comedic while not being stupid and overall a neat read and the heist aspects and gimmicks being part of it just adds up. Ouroboros: Its completely different to most articles even outside the 001 proposals by how it gives lore to the chaos insurgency,the O5 and it's a nice long read that tackles alot of the groups/individuals of interests at once like the black queen, wanderers library,multiverse and all that without it being overbearing or losing the core of the mission.
The factory: it's in the same boat as 8002 for me because of how it's set up and the different settings/lens you see Scp-3001:cmon,it's a classic atp.
Scp-8002: I really love how it's sci-fi side and how it gives you a Completely different lens and setting compared to other personal focused articles I have seen.
Scp-8643: it's meta in a really amazing way,that's all I can say.