There are a number of reasons why the earth is more habitable than other planet and I'll list them out and try to explain them as best as I can.

1. The earth is located in what is referred to as the habitable zone. It isn't too close to the sun and it isn't too far from it. If it shifter by an inch either way, it would either become too hot or too cold.

2. The abundance of carbon, oxygen and water which are the building blocks of life. Carbon which is found in just about every life form on earth is present and easily bonds with other elements available. Oxygen is present which lets human beings breathe. Water which no life form on earth can live without is also present.

3. The earth's insulating atmosphere protects the planet from the harmful electromagnetic radiation of the sun.

4. The earth recycles everything and as such nothing is truly ever wasted, everything that is used up goes back to the earth in one way or another and this has helped sustain life on earth.

I hope this answers your question.