Version 10.4.1 is the last iTunes that doesn't annoy at startup with a "Can't Connect to iTunes Account" message on non-network Macs.
That makes it quite useful on older machines in garages and basements and such.
Version 9.1 still manages an 80 gigabyte+ library handily on a 400mHz iMac, maxxed out at OS X 10.4.11; so long as you don't use too many "smart" playlists.
4 was nice too. I'd probably still be using that if I hadn't updated so often back in the day.