One very big advantage that acrylic carries over glass is that it's just a snap to drill. Just about everyone has a drill either in the workshop or in a closet. A little preparation/reading and the right size hole saw bit and you're good to go with a slow and steady approach.
Glass can certainly be drilled, but diamond hole saws and the tools required may be out of the reach of most, but is certainly something worth looking to having done for you before taking the plunge, or at the very least practicing a bit first.
Also, most glass tanks 55G or bigger have tempered bottoms that just cannot be drilled. Depending on the Mfr. smaller sizes have tempered bottoms too, and there are those unconfirmed stories of the 100% tempered 55G's.