It depends on how you plan to use the bicycle. For racing the smaller and lighter and stiffer frame has been considered the way to go. But for triathalons and touring a large frame that allows the rider to stretch out is a better choice. I am 5'9" and the charts put me on a 54-55 cm frame but other than a Dave Scott frame made for triathalons, I have used a 59cm frame with relaxed geometry for my thousand mile plus touring. With mountain bikes it is even more variable depending on the type of bike (downhill, XC, trail, etc.). On a 55cm frame I need to use a long stem to get enough reach so I am not bent up on the bike and I can make full use of my lungs and back muscles. The new (to me) stems that provide for adjusting the angle and height of the bars are a great option.
In your case I would try to find bikes in the brand and sizes you are considering even if they have different components as the frame what matters most. Interestingly enough most new bikes are sold in XS/S/M/L/XL frame sizes and there much less granularity in frames available. For me the focus then becomes on the head tube angle and fork rake of the different bikes in my approximate frame size.