I'd guess that a microwave would "waste" more energy as it's got moving parts and the energy isn't completely directed to heating the water. A kettle also "wastes" some energy as you end up heating the kettle too (from the hot water).

If a microwave was more efficient, I'd expect to see premium kettles that used microwaves instead of a simple heating element, though maybe there'd be design problems with preventing leaking microwaves.

Agree, at least to some extent.

For my use cases, I’m not looking to actually boil the water, bringing it up to 80 plus degrees suffices.

The inefficiency kettles bring is the tendency of certain users to heat way more water than their immediate needs.

I've tried that, and there are two problems. One is that water has a tendency to superheat and then boil all over the place when you put the tea in, or it suddenly produces a big bubble and water goes everywhere. The other is that it is hard to get a consistent temperature. Even if you measure it with a thermometer it seems problematic (although perhaps the grocery store thermometers go out of calibration easily). If you're doing herbal tea it might not matter as much, but for something like Chinese green tea, it was always hit or miss. I bought the Bonavita kettle as soon as I found out about it, and now I always have consistent tea with no fuss or mess.

My daily driver, a flatbed Panasonic microwave, does a good enough job, but yeah actually boiling the water in a microwave is a recipe for a way too hot cup, and half the water boiling over.

220ml, regular ceramic mug, one minute forty, does what I need, but I’m not tea or coffee connoisseur, just a prole with a box of Twinings loose leaf.

Thanks for the kettle reference, I have been meaning to find a temperature controlled unit.

I recently picked up an inexpensive Thomson branded electric frypan with digital temperature and time controls, well impressed.