I'm choosing column 6 because it creates a strong horizontal threat with three O's in a row (at positions 5,4; 5,5; and 5,6). This forces my opponent to respond to this threat. If my opponent doesn't block by playing at position (4,6), I could potentially win vertically in a future move. Even though I can't win horizontally in the next move due to the X at position (5,3), this move gives me the strongest strategic position compared to all other options.