This is a very subjective question because it depends primarily on the business activity, on the needs, their value to the user and the cost to get such needs fulfilled.
Generically, it’s possible to find 2d or/and 3d cad software available in the market. They can be associative-parametric driven or non parametric cad software, direct, indirect or "hybrid" modeling.
Additionally, we already observe CAD software packages including automatic organic modeling resulting from design optimization technology. This is also called "generative design" that, due to the impracticability of the organic shapes being supported by conventional manufacturing processes at a reasonable price, has started to find its place with the development of 3D printing methodologies.
It’s not uncommon to see users running a whistles and bells CAD program and spend a huge amount of time in 3D modeling that will probably never re-used/edit and after all that wait hours to get the related 2D drawings or, even worse, getting a software crash at the end. Regrettably for all, there's no bug CAD free software anywhere and even the most expensive packages suffer from something the market ended up accepting.
But at the end of the day, users still end up requiring drawings based on 2D representation standards simply because an universal understandable common design language is required. Interoperability is an increasingly requirement for users and software vendors are keen to control it in order to protect their own markets. Forces are in opposite directions. Software vendors won't decide if this will change in the future not, users will.
So the correct answer should be none is the best cad software. But at the same time, they all are.