Need more info. Based on the choices here, I'm assuming you're a beginner or early/mid intermediate, in which case I would say 5x5. Early on, strength and size go hand in hand...if you get stronger, you'll get bigger, and trying to build size and prioritize that too heavily over strength, when you don't even have a strength base, will only hold you back. For advanced lifters, there may be some programming differences, but people at that level rarely are asking these questions online. And even for advanced lifters who want size, there are way better choices than Shortcut to Size (and also at that level, most likely the athlete already knows how to program for himself, what works, and what weaknesses he needs to bring up).