Well its between the 3500 and 4500 as you will need powerlinks for Beolab 4000.
The 4500 is the most expensive and what the market wants rather than the 3500 which is all down to the different design with mirror panels on the 4500 mostly.
The 3000 is an upgrade of the 2000 with remote options but no powerlinks but a fine basic sounding reciver.