I'll play in column 1 to build on my existing position. By placing my piece at (5,1), I'll create two adjacent pieces with my existing O at (5,2), starting to build a potential horizontal win. My opponent has two X pieces at (5,3) and (5,4), but they don't pose an immediate threat since they need two more to connect four. Playing adjacent to my current piece is better than starting isolated positions elsewhere on the board. Column 1 also helps me maintain presence near the center of the board, which offers more winning opportunities through horizontal, vertical, and diagonal combinations in future moves.