Sorry for reviving an old thread but the article here (which is linked at the bottom of one of the guys who commented) is a must read for those intending to upgrade their Macs to SSD.
The article is here:
http://blogs.helsinki.fi/tuylaant/2014/01/upgrading-old-macs-to-ssds/
I've done upgrading for a few friends and referrals from friends who have Macs. Besides OWC, which is expensive in my opinion partly due to shipping, a decent alternative that won't go wrong is Crucial. Crucial BX100, MX100 all use controllers that work without issues with Macs. They also belong to the company Micron, which Apple uses for memory.
Even though the newer Samsung Evo 850s don't use Sandforce controllers, I've had an issue where the OS X will install into the SSD, but refuse to boot. I resolved the issue by cloning a pre-installed OS X from a USB drive into the SSD.
That said, I think specs on paper wise, OWC and Samsung might be a tad faster than Crucial. But in real world, you probably won't notice the difference so I'll rather go with Crucial.