MT66 is more like SLX I think – Shimano have XT and XTR branded wheels as well.
I had a pair of 26″ MT65s and they were easy to use tubeless, light enough and tough enough. Odd spokes and nipples though. At the time they were the cheapest tubeless option I could find.
I was looking at 29″ tubeless wheels yesterday – apart from the MT66s the cheapest light-ish pair I found were Actionsports – 1720g, about 270€ (depending on shipping) DT swiss 370 hubs and their own Atmosphere SL rims – seem similar to Crests in width and weight, but my German-language googling isn’t good enough to find out what people think of them.
Lots of other choices from Actionsport or Superstar for around 350-400 €, but then you’re pretty much up to the budget for a set of Light-Bicycle carbon wheels (around $600)