This answer was to the question: Is Adobe CC better than Adobe CS6. The original question did not specify Photoshop nor was it asking for differences.)

I’m sure it depends on the specific program. There hasn’t been any “must-have” features for Photoshop or Illustrator since CS6. Cumulatively though, there may have been a big leap in efficiencies and performance. This may also vary by what hardware is running the software. Some features, even in CS5, needed higher end graphics cards.

I’ve used the latest Illustrator and Indesign CC versions. Illustrator crashed quite often. Indesign is fairly stable, the only flaw that comes to mind is the shortcuts stop working sometimes (which can be awful).

Illustrator is the Adobe product I have the most experience with. CS5 is the best version. It is more stable than CS6 (in my experience). It has multiple artboards, which were added in CS4, and these turned Illustrator into a layout monster, surpasing Indesign in many aspects. CS3 was the last time smart-guides were perfect. After that smart-guides got a little too predictive, and they often just get in the way and/or lead to small but noticeable errors.

The real reason illustrator CS5 is the best is because it’s the latest Illustrator to support the Scriptographer plugin.

CS5 though, that seemed like the last time Adobe cared about its users and not its stockholders. Understandable though. Their products were pirated by the time they would hit the market. The subscription model has gone a long way to stop this.