If your getting both around the same time. I recommend getting the BN bigger so it can keep up with the pace that the oscar grows at. That might cost you a little though. The common pleco does grow faster and IMO
has a lot more character. In my experience of owning them for over 15 years. Can't go wrong with those
just gotta have the right amount of tank size. If you don't want a common or don't have the space I recommend looking into the different breeds including the BN.