NeXT
Deserves much more praise than it ever got.
My professional IT life started with NeXT computers - using them for various RAD work at Bt Laboratories through 1994-2001 (going through openstep and finally webobjects).
the OS, as well as the whole IDE and the core and enterprise objects frameworks were literally 10-15 years ahead of their time.
In 1995 I was easily building complex UIs with drag and drop, real OO behind them, and backed by performant object relational frameworks.
The hell that was/is J2EE has arguably not gotten to where EOF was in 1995, 20 years later.
Even in 2000 when I was using WOF - it was in a another league from everything else - and yet it just never sold - it couldn't get a shoe in the door with the big boys - though a few large sites used it (bbc website, apple's own, etc).
But back in 1995 it was like using something from the future.