For the kind of street photography I do, I'm fond of -and used to- the Fujinon 18mm and its 16mm sibling. The former is my go-to lens when I'm out and about on a simple walk-around, while the latter gets used when I know I'll be in a crowded spot...a demonstration or a festival, as an example. On occasions, I fit them on my X-Pro2 and X-Pro3, and have the best of both worlds.
I was recently interested in expanding -or diversifying- my street photography lenses, and looked at the Fujinon XF 27mm f/2.8 R WR lens, which is a "pancake" and retails between $400-$500....but at the time I looked, it was also listed as out of stock at the retailers I use.
I then chanced on the TT Artisan 27mm f2.8 which is Chinese-made, is one of their few products having auto-focus and retails at $149. I took the plunge and ordered it...and have used it for the better part of 3 weeks.
I never expected it would produce the image quality of its Fuji counterpart, but I found it to be quite impressive despite being a little "soft" at some apertures. However, it's a pancake and weighs just 3.3 oz. Some reviews claim it gives off strong vignetting from f2.8mm to f8mm...but I didn't find that to be such an issue for me.
I think its price point, sturdy construction, quick availability and especially its portability are enough justifications for my having bought it. There are in-depth reviews about it all over the internet, so readers of this post can make their minds up if needed.