Editorial headnotes. A headnote drafted by a trained editor, with the ratio separated from the obiter and the propositions numbered, is a piece of legal work. It is what lets a senior read forty judgments before a conference instead of four. Nothing generated at speed substitutes for it, and we do not claim to.
Decades of ratio tagging. The SCC editorial apparatus has been built continuously for a very long time. When you are working through a line of authority from the 1960s forward, the accumulated tagging and cross-referencing is doing work that simply is not available anywhere else.
Parallel citations to older reporters. Appellate practice still runs on parallel citations. If your list of dates has to carry AIR and SCC references side by side, the parallel citation tables matter more than any feature comparison.
The citation benches expect. This is the practical one. In many courts, in many matters, the SCC citation is the citation. That is a fact about the profession, not about software, and it is a perfectly good reason to keep a subscription.