I am going to pick my favourite three programs of all time here.
Firstly it was this..
Starglider (Amiga)
This was the first thing I saw on the Commodore Amiga, I really couldn't believe what I was seeing. At the time I owned a Spectrum +2, a mate of mine had worked all summer to save up £400 to buy a Commodore Amiga, he bought the computer and hooked it up to his stereo system.
I remember watching Starglider and it blew me away that it had stereo sound, no attribute clash and you could fly through the planets, it was such a huge leap.
He went on to show me some other things that were breathtaking, such as F18 interceptor, RSI megademo and many others, needless to say, the Amiga quicky became number one on my most wanted list.
Mental Hangover (Amiga)
When this came out my love of demos was already firmly ensconsed. I totally loved demos but this one was different, it had some generic stuff, such as bobs, but this was done in a different way to all the other demos at the time,even the generic stuff had new twists on it, like fiulled bobs, and it dared to breathe new ideas into the demoscene. This was the first time that I had ever seen any kind of attempt to apply textures to an object, ok Stencils are only a step towards them, but in a scene where people were still releasing wire frame demos, this was truely awesome and for me it was the last time I ever had the feeling of "wow! how did they do that" until very recently.
Receptor (PC)
This is the only demo I have ever watched since Mental Hangover that gave me the same overwhelming feelings.
I even wrote "A powerful experience" at pouet because I could not even put into words how impressive I found this 4kb. For technical achievement it is mightily impressive but it's also entertaining, has amazing sound and runs on even my crappy old computer... And it's in 4kb...
This takes me back.
The Spectrum I had was 128kb and I am even more impressed about Receptor when I remember that fact.
It's a brilliant piece of work and I'd argue that it's one of the best demos that has ever been created.