Nadella nay not have experience running a complete major tech company...but he also doesn't have experience running one into the ground, or pissing away the majority of a client base.
Of all the candidates on offer so far, Nadella is the only one whose installation would restore trust in Microsoft for me. Server and Tools are the good guys of MS. The rest of these CEOs are either corporate pillagers, ultra-high-end niche pillagers or who have failed miserably (repeatedly,) at targeting the consumer. Nadella is the only "make the best widget for the largest number of people at a reasonable price" exec of the bunch.
Everyone else at Microsoft seems to believe in Microsoft's manifest destiny. They espouse "metrics," but only as a means to justify decisions already made. Nadella uses metrics to guide descisions yet to be made, but also factors in actually talking to customers.
If you aren't going to install Nadella - and with him a demonstrable commitment to growing the compay, establishing and then preserving a technological leadership - then forgo the pretense and simply hire Ichann. At least he'll make the asset stripping and milking the husk for Wall Street's pleasure quick and relatively painless.
Whatever you do, don't put in some enterprise crony. Everyone in this business targets the enterprise almost exclusively. There's only so much room there, and Microsoft isn't well poised to win a competition for enterprise devices and services against the likes of Oracle, HP, IBM or Dell.
Stick with the mass market. Make good software, devices and services that are easy to use and at a price that the majority of individuals and businesses are willing to pay. There is no future for Microsoft excepting that. So far, there's only one CEO I've seen who could deliver it.
Which means, all told, we'll probably get Elop. *sigh*