Cassette decks. How good can it get?

I know some guys are going to just want to say a bunch of negative stuff about tape decks and tell me how bad they sound.  There is a lot of music that comes out on tape only (you usually get download too) so I have been acquiring quite a stack of cassettes.  I have a couple of Nakamichi decks BX100 and BX300. The 300 is not working and was thinking of trying to repair.  I am wondering how good of sound you can get out of cassette?  Has anyone taken the leap up to something like the much more expensive Nakamichis or other brands even.  I enjoy the sound. Mainly it's the background noise more than anything but even that is somewhat tolerable.