Column 4 is the best strategic move for several reasons:

1. Defense: My opponent has two X pieces in a row at positions 2 and 3. If they play in column 4 next, they'll have three in a row and be one move away from winning. I need to block this threat.

2. Offense: Playing in column 4 connects with my existing piece in column 3, starting to build a potential horizontal line.

3. Board Control: This move maintains control of the center area of the board, which is strategically valuable in Connect Four as it offers more potential winning paths.

4. Future Possibilities: From this position, I can continue building in multiple directions (horizontally or diagonally) in future turns.

Other columns like 1 or 5 don't offer the same combination of defensive and offensive benefits.