I dunno. Watch one or the other then tell us about it.
I ended up doing both, back to back.
Both films are interesting enough, without telling you very much (if anything) you don't already know.
There's a bit of overlap too
The Corporation is a long one, around two and a half hours, but I found it the most interesting of the two.
It's also the older, made in 2003, but holds up well.
It looks at the development of the modern corporation and features interviews with a wide range of people, everyone from Noam Chomsky to Milton Friedman (who also features prominantly in ther other film).
It also looks at a number of firms, including Monsanto and Coca Cola.
I'd recommend it to most of this site's users.
(I say most because Michael Moore is one of those interviewed and I know there are some on here who can't watch Moore without
)
Shock Doctrine is a look at the implementation and spread of Friedman's economic ideas. It starts with Naomi Klein giving a speech, before moving on to Pinochet's takeover of Chile and following things from there, all the way through to 2008. It's much shorter, around 80 minutes or so.
It's newer too, from 2009.
I'd say The Corporation is more balanced and held my interest better but they're both decent enough.