What is the best Automatic Transmission Fluid for a 1996 (7th gen) Mitsubishi Galant?

Do I have options? I mean like I want to make the best or squeeze a little more power from an Automatic . Can you suggest for a better Automatic Transmission Fluid that should suit my 4G63 galant? Please post what brand and what type. Also, I saw several Automatic transmission fluid additives around, do you guys think they're worth the price?Thanks