The decision depends on your needs. If you are running two main lines and some accessories, with normal to moderately heavy power demands, a Z4000 is more than adequate. If you really need the extra 200 watts, the ZW-L starts to look better. Given the extra cost, I see it as justified only if you need the power.
The ZW-L has two extra throttles, but they are very inconvenient for conventional operation, since they have tabs rather than handles. If you have main lines that will ONLY be used with command control, then you can set them and forget them and it's fine. They are also good for accessories that require adjusting the voltage for optimum operation.
I prefer the digital voltage and amperage readouts of the Z4K over the analog dials of the ZW-L. Analog is cool and retro, but the big red numbers give you instant information. The ZW-L is better looking - I'd call it a Deco piece, while the style of the Z4K is more Brutalist.
The chopped sine wave operation of the ZW-L is superior when operating a TMCC locomotive in conventional mode. I took a very close look at the Mike Reagan video and I did not see any operational advantage in command mode.
You can use the Z4K for remote controlled conventional operation by getting a Z4000 remote control set or receiver. The receiver also works with a DCS remote.
I use a Z4K at home and I am quite happy with it. I have four main lines, but I prefer to have a separate throttle handle for each line, since any line may be used for conventional or command operation. For the other two lines I have a TW (Standard Gauge) and a K-Line Power Chief (0 gauge, short radius inner line mostly used conventionally). I'm quite happy with this setup, at least for the moment.
Our museum has used Z4K's for over ten years and we like them fine. No plans to change.