I would recommend R. It's the language college grads are getting trained in. The reason for that is simple. There's no licensing costs for a simple R dev environment. However, I wouldn't use the free stuff for anything that ad hoc. If you have a production big data job I would look at something like Vertica (purchases by HP a couple years ago.) Extremely fast big data DB engine. Not only will it run R, but it has the ability to break the R up into smaller chunks at execution time and distribute the execution across the DB cluster.
Stuff like that just isn't possible in SAS yet. SAS is built upon some very old skool constructs that make it very brittle and very difficult to meet the performance expectations of todays big data world. SAS may end up there, they are privately held and have a very large R&D budget, but I think they would have to do a total rewrite for it to compete. Not that SAS is going away, there's just so much of it in the business world. Be that as it may, in 15-20 years SAS could be a Foxpro of it's age.