Definitely a combination of nostalgia and the "wow" factor of seeing the sound and graphics capabilities for the first time... as other have said...
I had a Vic-20, then C64 before I had the Amiga and the jump in capabilities was mind-blowing at the time...
I'm not really interested in the 'modern' so-called Amiga OSes or generic PPC boxes, they're something quite different.
The good old days where the Amiga ruled the roost were the best, and now they're just a fading memory...
Mike.
P.S. This thread would've been a good candidate for a Poll! :-)