What system were you impressed by the most when it first launched? This could be because of the system's graphics, features, launch titles, etc.
I think I was the most impressed by the Dreamcast. Its graphics were such a HUGE step up from N64 and PSX. I remember how amazed I was when I first saw Sonic Adventure, Soul Caliber, House of the Dead 2, and NFL 2K in action. Not to mention...it had the best lineup of launch titles out of any system I can think of.