Having used a lot of SPARCs and NeXT boxes side by side during that period, I'm scratching my head as to what features you're referring to, at least among machines which directly competed with, say, the NeXTstation Color Turbo. Looking back I'm really amazed at how ahead of its time that machine was.
But the critical item, I think, was the OS. NeXT had NeXTSTEP. Sun had heaven help us all) SunOS and later Solaris. SGI had IRIX. There was absolutely no comparison. I think this is why NeXTSTEP still lives on in OS X, and Solaris, um...