Interesting observations ... I also like the 20mm f/1.7, and I do like shooting it on the GF1; on the GX9, the 15mm f/1.7 gives me more satisfaction and even better results, but given the difference in price, this shouldn't really come as a surprise. However, there's a measure for my appreciation of the lens: Sometimes, I'm tempted to also get the 20mm f/1.7 II just to try it on the GX9 ... (I know it's not really a different lens, but still ...).
I also really like the results from the Fuji 27mm f/2.8 - it's another strong performing 40mm-e pancake.
That said, I also like 45mm lenses - my current personal favourite AF lens is the Sigma 45mm f/2.8 C that I currently have to shoot on the Sony A7 II, a camera that's decidedly past it's sell-by date - I really hope Sigma will be able (as well as willing) to crack Nikon's Z mount protocol and give us this lens in that mount. I'll get that lens as soon as it becomes available ...
Oh, and the actual reason why I'm posting in this thread: I got another Contax Carl Zeiss 45mm f/2.8 Tessar to replace the one I busted ...
View attachment 222858
It's in a bit worse nick than mine was before the tumble, but the cosmetic problems are minor, and I got it for comparatively little money.
M.