do you like it just because it is the greatest animal on the surface of the earth?
I think it is not convincing enough. And how would you define the greatest animal? I think if you change another more exact words it will be more effective.
My favorite animal is the king of the jungle---(the) lion.Without any doubt it is absolute the most energic and full of fighting power animal; this is the reason why it could be the king of the forest and also why I like it so much.
(But how will you going on describing it ? As for me, I did not contact with a lion, so this article is a little hard....., looking forward to reading your essay. )