That's really a very good list, Mo.
All of them are fantastic discoveries/inventions/breakthroughs.
Hard to classify any individual one as being the 'greatest'. Many are related and/or interdependent upon each other.
I'd vote for the harnessing of electricity. My reason for doing so would be that the harnessing of electric power, in my opinion, has had the greatest impact on the lives of people living in the civilized world today.
As Muman pointed out, transistors and computers aren't even possible without electricity.
We tend to take for granted the conveniences and essential services that are made possible only with the advent of electrical power.
Imagine no light bulbs. Imagine no refrigeration or air conditioning. No television, radio, movies.
If your power has ever gone out for a prolonged period, I'm sure you know how much we depend on electricity. It's hard to imagine living without it.
The harnessing of electrical power has had a profound impact on the development of modern civilization. And since electrical power is the backbone of information technologies, we've only scratched the surface of it's ultimate impact on humanity.
PS to muman613:
Your thanking Hashem for creation, although done tongue in cheek, really is the bottom line. Of course, anything and everything; space, time, our very existence, is only possible because of the creation of the universe.
I believe it was Nachmonidies that said there was only one physical creation. This initial creation was the size of a mustard grain and a 'substance without substance'. Fascinating, isn't it ? A substance without substance. Sounds like he was talking about a bit of pure energy somehow expanding and coalescing into protons, electrons, atoms and eventually all matter itself. Similar to how modern physics envisions the Big Bang. Nachmonidies also states that time 'grabs a hold' only after matter coalesces. An amazing insight, and one that should make any agnostic question where such knowledge could have come from.