Well as you can see this thread hasn't made it any more clear. I do have to put my vote with the A3000 as well though. Why? Well when te system was being developed the engineers were a lot better. They put everything in sockets, the board is very well made, it's case is built to last as can be seen by just how many are still in use today. It came with everything every Amiga user was asking for out of the box, and you paid the price for all that too.
The A4000 was a cost saving version of what the next A3000 was going to become. The engineers for forced to make cuts, built it as cheap as they could, and take a lot out of what they wanted to put into it. In the end it had a lit of great features, but nothing like the A3000+ has and I know, I have one and it works. All of this lead to a ton of dead A4000 systems, a ton of revisions to attempt to fix the issues, and resulted in a even poorer model in the end. How many have seen the cost reduced version of the A4000?
So in terms of engineering and design the A3000 is by far the best Amiga ever produced.
Oh and for those saying the A3000 cant take a mediator? I think you better look again, mine has one in it and it s working great with a Voodoo 5, a soundblaster card, a 100MB ethernet card, a USB card and a TV card in it.
http://buy.elbox.com/cgibin/shop?info=209M3D&sid=266e2c82