OK, I see it listed as "Mac Tower Duo" or whatever you've got there. Guess I missed it-- it's official name actually
is Macintosh Pro.
No 20th Anniversary? Awww, but Seinfeld had one in his apartment during one season of the show...

What about the Plus? You can't discount the Plus! The Plus had the longest production run of any Macintosh model.
And the SE/30? Despite having a similar name and case to the SE, inside, the SE/30 was nearly 100% different. The most powerful of the B&W Macs, the SE/30 was essentially a Macintosh II all-in-one with black and white video. You could even install a color video card and get high resolution color on an external monitor, and greyscale on the internal screen!
And finally..... What about the Apple I?
In all seriousness, I voted for the Apple II series. This line of computers, while each model was drastically different, revolutionized the PC industry.