I have some Fiberology PA12+CF15 blend (link) from a long time ago and recently got around to using it. I am amazed to say the least! It prints easier than PETG, even without an enclosure. Only downside is that it is much more expensive per kg, although it is lower density so I don’t seem to be going through it as quickly as other filaments.
I recently purchased some PC Blend with CF from Prusa as well. I haven’t gotten to print it yet, but I’ve heard very good things about it, too.
What less common filaments do you fine folks like using?
Filamentum TPU 98A is probably the toughest filament you can buy. If you are ok with a little bit of flex, it’s basically impossible to break any parts made with this stuff.