I find it interesting how much opinions on this topic differ.
Personally, I think it has been a strong year for the Mac, one of the strongest in recent history – two long-awaited, exciting redesigns that both do most things right, the completely new iMac Pro that offers some invaluable choices for the professional market and is presumably a harbinger of things to come with the Mac Pro next year, and also a solid and actually quite significant upgrade of the MBP line, with some surprises that most people didn't expect such as 32GB of DDR4 RAM or the 4TB storage option or the recent addition of the Vega graphics or even the i9 spec option. The T2 chip is a bit of a controversial point because of the Kernel Panics that some people have, but other than that the chip also does many things right and has a bunch of meaningful even if only minor improvements, security- and otherwise, that might prove very valuable in the long-term. And Mojave also was one of the best and most feature-rich macOS-versions in recent years (and despite that had a much more stable and smooth release than High Sierra last year). Not to mention the upcoming Project Marzipan – if executed well, it could be one of the biggest software-additions for the Mac this decade and fundamentally shake up a rather stale app market.
Apple's quality control is a bit worrying in some places, and I definitely see why you and other people are willing to leave Apple behind because of it (I have concerns about it aswell). But other than these issues (which shouldn't be ignored, but also shouldn't be blown out of proportion) and the unnecessarily increasing prices, I think Apple is on the right track for the Mac. If we get hexa-core iMacs and Amberlake MacBooks in spring that are similarly good like this year's refreshes/redesigns, and the long-awaited new Mac Pro alongside new Apple displays sometime later next year, alongside the "usual" refreshes like the MBP when the 9th gen of Intel's chips are out, then Apple is IMO on a good path with the Mac. This year definitely proves that they haven't forgotten about the more professional parts of their customer base.