Fantasy vs. Science Fiction

by the way, maybe in the future our life will be sci-fi

Approximately, that might be the case, but our understanding of the future is still quite primitive.

Again, while reading Meggot's post, I want to clarify that sci-fi is not just galactic-scale wars, not a distant future or distant galaxies. It can even be our present day. For example, a time machine was invented, and the characters end up not in the future, but in the distant past! It is enough to change one important detail in the modern world, and essentially you get sci-fi.

if we consider the worlds as a whole, which one would you like to live in?

It depends on who I am. :) Either a simple peasant or a hero who saves the world. Personally, I would never want to be a peasant in a medieval world... A hero? Yes, from the reader's point of view, it looks incredibly romantic, and his adventures seem incredibly exciting, but it is not a fact that the hero himself thinks so :)