My vote still goes for the 9000.
I'm biased as I had mine for 5 years now but it has the most technical options and I play all kinds of tapes mostly good ones but it always the best sound it can do. A well recorded tape can sound as good as the radio or record.
I also have 6000, 8000 and 1900. At present needs to go to Dillen for minor work but they also have good strong build wit just as good sound but less options.
Back when I had the 2000 system(80s) that Beocord was just as strong as the 9000. Recorded and played nearly the same.
The only drawback is that belts needs to be changed but you can't go wrong with any of them.