OBA vs OFT
I went through the same OBA vs OFT depate when I was deciding where to finnish my PPL. For me cost was a big issue so I listed all the costs and OBA came out as the clear winner. With OFT there are alot of additional charges that you need to take into account. $50 hotel per night, SEVIS, TSA, fingerprints.
Obviously this is only one criteria to basee a decision on but if cost is a deciding factor its good to list everything out.