If you're about 15 minutes away from San Beda, it means you live around the Taytay/Antipolo area. That's really far from LSGH considering your child has to take the Ortigas extension route everyday.
Anyway, my husband is an alumni of LSGH so I'm kinda biased on this. He's from Binangonan Rizal and he told me na everyday non, he'd be en route to school as early as 4 or 5 am. La Salle Greenhills is a very good choice but I think you also have to consider your child's daily commute to school, that's a big factor, especially pag umuulan or what not. San beda naman I think has a nice curriculum din. They've even integrated Mandarin in their curriculum.
Have you also considered Ateneo? I prefer Ateneo over LSGH (and my husband knows this), kung magkaka-baby boy kame, I would definitely want him to go to Ateneo.