For me, the free machining leaded steel 12L14 is very easy to cut, but
bad for lapping together parts, because is galls so quickly.

For me, the tool steel, annealed 4140 is easy to drill, until the high
speed drill gets dull, and then the 4140 gets locally hard. I have to
order a carbide drill of that size to cut through the hard spot.

For me, 1018 steel is the go to steel.