Well, the 4000T was the best Amiga money could buy :-) , and the reason i bought one instead of a regular desktop. But it is really a terrible design, you only have 5 5.1/4 external drive bays to put drives into, no internal(!?), and you must use some hard-to-get drive rails to mount any drives there as well. The onboard SCSI is not DMA and on my 4000T it refuses to work with HDD's...
Also the serial and parallell ports, audio/video&RGB ports and the SCSI/floppy ports are mounted on "modules" connected to the MB, with either flat cables or sitting directly on some pin-arrays. Really a troublesome design, as the case is very un-rigid when the cover is off and you risk bending everything out of their connectors :-(
All-in-all, I would say the desktop is a much better designed piece of hardware, but the 4000T is more rare...and the one you would want if you were to collect Amiga's :-D