Software-wise, either OSX or the iMovie - iDVD combo. The former is just too cool, and the latter did for video editing what the word processor did for text. Easy, clean, fun, and produces a truly professional looking product.
Hardware-wise, it's a toss up for me between the Apple //c (boy, those were fun), the Cube (I never owned one, but every time I see one I marvel at it), and the iMac line--all of them.
I say the entire iMac line because I had just been thinking about its progression through the years:
With the original iMac, Apple changed the computer from a utilitarian box into something friendly, cute, and personal.
Then, with the slot-loading design, they increased the transparency and made the two upgradeable parts (RAM and Airport) really easy to get to, demystifying the guts of the computer a bit--it said "Yes, I'm technology, but don't be afraid".
With the G4 iMac, it shed the traditional shape of the computer entirely, introducing people to a computer that doesn't look like a computer at all.
Finally, with the G5 iMac, all that comes together--it doesn't much look like a computer at all, now more of a minimalist piece of furniture, and its design is such that anybody can pop the back off and do maintenance on it. It is simultaneously invisible as a computer while allowing even novice users to perform fairly heavy-duty maintenance on their own system.
More technical and less technological, all at the same time. Neat.