I had to replace my home HVAC system this year and went with a variable speed system. It was eye-wateringly expensive, but it works much much much better than the system that was in here before, and completely obviated my concerns about sizing (the old system was an oversized single-stage unit, and the house always stayed cooled, but something or other was regularly breaking, probably due to the short-cycling).

With the new system, electricity consumption on a hot summer day is about a third of the prior system, it’s virtually silent and the comfort of the house (due to more granular temperature control and near-constant dehumidification) is substantially better.