Glass is harder to move, harder to scratch and easier to break. So, if you (or your relatives) are careless around the house avoid glass. If you are careless in your maintenance (cleaning) avoid acrylic. The costs of the tanks are significant to some so I'd consider that as well, but to me the cost and aggravation of a broken (glass) or scratched (acrylic) aquarium out weights that. I think it's a bad plan to get a tank that one plans to crack or scratch simply because it would be easier to repair.
Honestly, I think it's a lifestyle question, but the really large tanks become a major weight issue unless the tank is built in situ or you plan on professional movers. If you are prepared for the tank to break or to replace the tank if it's horribly scratched, then either one works.