I personally use some french solder(mbo), 1 mm diameter, with 60% Sn, with my small 15 W iron, for small work, and some german (stannol),1.5 mm diameter, Pb70sn30 with my 60 w iron, for larger wires.The 15 W iron has a cadmium tip, which is supposed to last indefinitely (I bought it in the
80's) and the other is from the 90's.