PIC32MZ series only work with 'Harmony'
That would be sufficient enough to strike PIC32 off my list of mcus to consider.
The underlying statement is blatently false.
Harmony only works with the PIC32 series of parts, but you don't have to use Harmony to use PIC32MZ. Just like you don't have to use the Microchip MLA to use a 8 or 16 bit part.
All Harmony is is a set of libraries for the PIC32 family which includes such things as a USB stack, full TCP/IP stack (with numerous protocols supported), interface with RToS'es etc. You don't have to use Harmony if you don't want to.
You also don't have to use the microchip toolchain. Or at least won't have to soon. I know of at least 2-3 tool vendors who are in the process of updating their toolchain for the PIC32MZ. Heck, if you're an Ardunio fan, you can go buy a ChipKit Wi-Fire to get started, and use ardunio tools to program the PIC32MZ. Personally I like MPLABX, find the compilers for the PIC32 be not bad at all, especially for free. Harmony is maturing, and is a good spot to get a jumpstart on a bigger, professional, project which is what it was intended for.
Having had some heart-to-heart discussion with PIC32MZ design team members I know that they've had some challenges along the way. This is Microchip's first part on a new, smaller process, and things have definitely not gone as smoothly as they would have liked. Some of the early errata was just ugly. The ones that remain are actually pretty typical of a newer part, and aren't show stoppers for many applications. Compare the severity of the current errata with the first release of almost any other 32 bit MCU and you'll find a similarly sized list of similar severity issues.
Honestly, the PIC32MZ is a big, fast, low power consumption MIPS core MCU. If you need something which runs at 200Mhz, has 2MB program flash and 512K of RAM and numerous onboard peripherals, this is worth considering.