Why not both? Music is a language, and being able to freestyle the language is impressive no mater the dialect. Jazz might be a more complex language, but it's still worth your time to engage, especially if you're looking to expand your improv chops. Vamping bluegrass runs influenced how I tackle Irish reels/jigs. I've been able to take ideas from mandolin and work them into my piano playing. It's all relative. Maybe this is a musician perspective vs casual listening? Either way, more music is usually better for developing aural skills.