Any MacBook Pro with model identifier of
MacBookPro10 or less does not have an UEFI. MacBook Pro (15 and 13 inch, Mid 2012) computers have model identifiers
MacBookPro9,3, respectively. The MacBook Pro (Retina, Mid 2012) has model identifier
MacBookPro10,1. I assume your model does not have a Retina display, therefore I assume you should install using a BIOS/MBR booting.
I hear UEFI offers faster booting. I also hear this requires a single boot configuration. Well, you will being dual booting with OS X, so you can't take advantage of this feature anyway.
Another advantage to UEFI booting is access to a larger number of partitions. UEFI booting uses the GUID partitioning table (GPT). This has default limit of 128 partitions. BIOS booting requires Windows to use the MBR partitioning table. This limits Window access to only 4 partitions in the GPT. On Mac computers, generally 3 partitions are used by OS X, leaving a single partition for Windows. There are ways around this single partition limit, but this requires abandoning the use of the Boot Camp Assistant.