Two thresholds. I aim for both.
The web has two accessibility tiers worth caring about. AA is the legal floor in the UK under the Public Sector Bodies Accessibility Regulations and, for many commercial sites, the Equality Act 2010 — it covers the basics: readable contrast, keyboard navigation, semantic markup, sensible alt text, sane heading order. AAA is the enhanced threshold — 7:1 contrast for normal text (versus 4.5:1 at AA), stricter heading order, unique accessible names on links serving different purposes, fuller keyboard parity, and a number of smaller refinements that add up.
For client work I aim for AA at minimum, because that’s the legal bar your business needs to clear and the moral bar your visitors deserve. Where the design and content reasonably allow, I push to AAA — which is what flexiweb.digital itself is built to. Not as a brag; as a worked example.