can't tell, because they are so different.
at&t doing phone and isp but not serious in Software
and microsoft doing all (more or less) serious.
for infrastructure: i would say at&t, they turn of their fiber-cables and nearly no internet anymore
for software: i would say microsoft. if they go after all of their windows copies and call for licences and sue! the world will sink in bankruptcy and courttrials.
my 2c
Mike