I'm a "love the one you're with," and "pick one, you gotta be kidding," kinda guy, so...
My current gear makes me very happy: Late 2013 iMac 27" with 3TB Fusion - largest display I've ever had, speediest computer I've ever had, and quite sexy to look at. Close behind that comes iPhone 6 (I have plenty of respect for the iPhone 4 that preceded it, but the 6 runs rings around it). Finally, iPad 1st Gen - huge game changer for me (no doubt my next iPad will bump it off the list, though).
My Hall of Fame nominee is Quadra 950. Pro desktop audio in the 1990s (Sonic Solutions software and DSP cards). Enough horsepower to concurrently record tracks in background while editing them on the fly (Pro Tools was PC-only, and didn't come close). Those were the days when the other truly pro digital audio workstations were running on minicomputers with dedicated hardware interfaces/work surfaces and hatbox HDDs, at Hollywood-production-budget prices... my favorite pro audio gear, both analog and digital - "game changer" is a gross understatement.