"Standard" velocity for 1 ounce slugs is up to about 1350 fps. 1 ounce slugs over 1400 are most certainly "Magnum" loads, at least based on SAAMI.

Having actually performed slug penetration tests (and at animals with body armor attached) for a few different groups, there can be significant variation in penetration with lead slugs: foster, wad, plumbata, sabot, that are traveling over 1300 fps, whether hard or soft. I am of the camp that a 1 ounce slug from about 1100 to 1300 that runs your gun and is accurate is about all you really need to worry about with a smooth bore firing full diameter slugs. That is true for defense against humans with body armor or not. When we tested slugs on engine blocks, the standard slugs were not as successful at stopping the engine from running as the hardened Magnum Penetrators.

I would not dismiss "weak" slugs like the Aguila. 7/8 ounce at 1200 is pretty decent, and if they run in your gun (P12, Win 1300, KelTec, SXP), they are a good choice.