Positions of drag wires in a bay
Neither. The best one would something between 2 and 3. The continuation of the wire should cross the intersection between the middle lines of the spar and compression tube.



In structures with two-force members, such as trusses and combinations of rods and beams with wires, the members are intended to work primarily in tension/compression. To achieve this, the middle lines of the cross sections of all members at a joint should intersect in a single point. If they don't, some of the members will have to carry additional loads such as bending or torsion moments.

Problems due to eccentricity at joints often show up as fatigue problems: even if the aircraft structure passes all static tests, the stresses due to the additional bending moment make the structure fail much earlier than it would have if correctly assembled/designed.