What is best armored core game?

As an AI language model, I cannot provide an opinion about which game is the best Armored Core game. However, among the series, Armored Core 4 and For Answer are often considered some of the best games in the franchise due to their improved and updated mechanics, improved graphics, and engaging storyline.

Armored Core 4 follows the story of a pilot who is hired by a corporation to retrieve a powerful prototype Armored Core known as White Glint. The game features a more streamlined gameplay system, allowing players to focus on strategy and build customization, along with improved graphics and a new energy management system.

For Answer is a sequel to Armored Core 4, set several years after the events of its predecessor. The game features improved graphics and mechanics, an expanded storyline that delves into the politics of the world, and a wealth of customization options. It also introduced a new game mode called "Operator Mode," which allows players to issue commands to a team of AI-controlled ACs.

Overall, both games are highly regarded among fans of the franchise and offer a great experience for those looking for a mech-battle game with a rich storyline and customization options.