Answer:

Our choices will not include anything negative or harmful; yet we will be faced with endless possibilities for personal growth and awareness of the Divine.

When Moshiach comes, the prophet says, G-d will "remove the spirit of impurity from the land."  Consequently, our appetite for evil of any sort will vanish, and negativity will no longer have any power.  At that point, the battle between good and evil will come to an end.

However, even though we will no longer struggle with forces of evil, we will still have the ability to choose how far we wish to advance in developing our personalities.  Our choice will not be between Good and Evil, but rather between Good and Better.  When our battle is between good and evil, we face a choice whether to improve or deteriorate, or use our powers for good things or bad.  However, when Moshiach comes, the option to do evil will no longer exist.  Our choices will be only in the realm of good.  We will choose how much effort to put into nurturing our talents and abilities, and in which areas we will improve ourselves.

Maimonides writes that when Moshiach comes, our sole occupation will be to know G-d.  Since G-d is infinite, we will have unlimited opportunities to expand our understanding of Him.  We will have the choice to know G-d through studying holy texts, through delving into the mysteries of creation, or appreciating the beauty around us.  We will be able to express our relationship with Him in myriad ways - through art, music, poetry, or through intellectual growth and advancement.  As mentioned, our choices will not include anything negative or harmful; yet we will be faced with endless possibilities for personal growth and awareness of the Divine.