Professional tools from manufactures which are be partly funded by the cost of the tools and generally have much better support than a bunch of hobbits on a forum. Not all open source/free tools are bad but may really are quite fractionanalized and with very arrogant forum support (if any).
It's interesting how this idea lives and lives. I do see it makes
sense and the idea is internally coherent, so it's a valid
expectation, but I'm seeing very little evidence that this is actually the case.
Quite the opposite has happened: "professional tools" have often become simple wrappers to run the open source tools. Many GNU tools, for example, have development history and tradition of three decades in them, and are used by almost anyone, hobbyist or professional. The proprietary part does less and less, and for a good reason: they have noticed it's better that way.
Whenever the "professional" tool is really a proprietary piece of software, it's quite common that it's an almost unusable piece of shit; but yes, if you pay enough, you'll get someone to answer the phone for you and help you out with an issue caused by their broken software.
This is the reality about most software development tools. In CAD, it's a different world altogether, where proprietary design software rocks and will probably do so for a long time.