I went through the same journey looking for a cheap vintage lens after getting the fuji 18mm, 35mm and 55mm-200mm.
I originally planned on one or two lens, but ended up with a variety collection of vintage glass. Because they are so affordable. I have found to love each for different reasons. In general, most vintage glass for me can get soft wide open (which I don't mind at all as most of the edges will be bokehlicious), but are still sharp in the middle. From personal taste, I have found that my favorites are (have not used any takuma or nikkor...)
Jupiter 9 (85mm f2.0)
Zeiss Jena Tessar (50mm f2.8)
Helios 44-2 (58mm f2.0)
Zeiss Jena Sonnar (135mm f3.5)
Minolta MC (58mm f1.4)
Meyer Optik domiplan (50mm f2.8)
I used the K&F m42-fx dumb adapter and it's perfect.
I have a few vintage 28mm as well, but they never get used over my fuji 35mm...