If you want to sound more native use ,,Mir geht es auch gut" as well as ,,Es geht mir auch gut". Both are common, the third one is rather rarely used but you can use it too You can also just shorten it and just say ,,Mir auch" but preferably amongst your friends. If you want to sound more polite you can add ,,Freut mich" in front of the sentence which would mean like ,,Nice to hear" or ,,I'm pleased". Which would be ,,Freut mich, mir geht es auch gut."

Susanne, thanks for the cultural detail (I find it VERY interesting!) and also for your suggestion nr.4 :)

My nr. 4: Danke, mir auch. Please note that in Germany, you'll often get a more detailed answer than you'd expected ;) Especially among closer friends, the beginning of a conversation will not run along those formulaic lines. Instead, the answer will be something like "Super! Ich bin endlich befördert worden!" (Brilliant! I finally got that promotion!") or "Och, geht so, meine Katze ist grade gestorben." (So-so, my cat's just died.)

I found the forum in which I had read that the three of them are possible. But I would like to know which ones are the most common/used by you and people around you. http://forum.wordreference.com/threads/mir-geht-es-auch-gut-word-order.2981145/ [Cuore Romano's answer]