So would they still decide to make autonomous machines? If yes, what would be different in their approach compared to an organic creation?
Doubtful. To maximize efficiency the AI would more likely go for massive clusters of supercomputers distributed globally, with an armada of "dumbed down" automatons at the construction and physical end of things.
My reasoning:
* Centralized AI - Decision making and thinking are complicated tasks. That's why we haven't had any success in duplicating this at levels where a general intelligence is created artificially. To have this amount of intelligence embedded to every mobile machine is a huge waste of resources, when compared to the alternative of a hive mind.
* No "individuals" - Same reasoning as above. Before long any AI among the many would come to the conclusion that individualism is still a waste of resources. Instead of having units, pooling resources saves both in space and time to learn things, as everything learned once is in the collective. 64
Writing this I notice my language drifting towards the Borg of Star Trek, but that was more of the example of a poor and wasteful design.
* Clustered - Currently we still have some constraints with global communications: There are some limits like the speed of light that are quite tricky to break through. Therefore it would make sense to cluster the mainframe, possibly have a tiny amount of redundancy in the system. Meaning the deletion of let's say two nodes out of a dozen wouldn't have any effect on the overall knowledge-base of the system, as a catastrophe fail safe. This would also be essential for time sensitive matters to reduce reaction times, like say controlling fusion reactions with magnetic fields and such.
* Specialized drones - The three points above lead to the third, which answers the question itself. An AI that I'd see realistically happening, as described above, would create autonomous machines. But they'd be simplistic, purpose-built things with barely enough automation to complete a single task should there be an error in the communication. Think more in the vein of a multitool attached to a quadchopper drone, rather than T-800. 64