I've had a few Xperias, as have some of my friends, and for us there's been no issue with cracks; it's not a problem everyone faces!
I've replied to your same question in the Xperia section, and reckon you should try both. I'm going to get TP2, compare with my Xperia, then sell the one I don't want, as both are great devices with relative good and bad points about each.
Current phone: Samsung Galaxy Note 2 LTE
Previous phones: HTC Kaiser, SE Xperia X1, HTC HD, HTC Pro2, HTC HD2, HTC Desire Z, Galaxy S2, HTC One X