I should play in column 5 to extend my horizontal line. This will give me three Os in a row (positions 3,4,5 on the bottom row), creating an immediate threat that my opponent must respond to. This is an aggressive move that forces my opponent to block in column 6 rather than pursuing their own strategy. It also balances the board by preventing my opponent from potentially creating a threat with their two Xs in columns 1 and 2. While there's no immediate win available, this move creates the strongest position for future turns.