I've recently purchased an M50, and am in the process of selling off various EF bodies and lenses whilst keeping some of my existing lenses. I'll probably sell my Sigma 10-20 in favour of the M equivalent, for example, purely on the basis of size savings, whereas my EF 28mm 1.8 will probably always remain as my main lens for most things.
The one I'm really struggling with, though, is getting my head round the value proposition of the 28mm Macros lens. I currently have an EF 100mm f2.8 lens and MR-14 ring flash. This has let me get some really great shots of insects, and especially when my kids were a bit younger, it meant we could go on a really good fun safari together, discovering all sorts of fascinating mini-beasts in pretty much any bit of open ground. I could, of course, use it with the M50, but the combined lens and ring flash are about 4 times the size of the camera body, so it's certainly not something I can just pop in a jacket pocket on the off-hand that I might see something interesting.
The M lens has all the benefits of size going for it, and I'm interested by the notion of having lights built in to the lens itself, but I'm perplexed by the focal length! Unless I cover flowers in superglue and wait for insects to land (which I don't, before I get accused of animal cruelty! ) it's often enough of a challenge to get close enough for really good shots with the 100mm lens, so how do people handle getting up close enough with the 28mm lens?