Earlier quoted context omitted.
Word for Dos 5.0. If you are old like me, you may remember thinking this was a pretty good word processor, and when Word 6.0 came out, it seemed a bloated mess in comparison. It's been downhill ever since. Mac OS X 10.6.8. It was good, and stable, and nothing that has come after has really added value to the product.
iOS 6. I'm using latest iOS and the only useful feature for me is fingerprint recognition and that is more about hardware. They added tons of new features but I wouldn't miss any of those features.
Snow Leopard, iOS 6, Word 6 (or 2003 if we have to take the modern era), all seem easy choices, yet the companies doing it never seem to notice they jumped the shark. Dropbox 10x the size with built in messaging anyone? Thought not. :)