Some are flimsier than others. My Motorola has been very tough, it has that special glass and a metal case, its been dropped a few times onto hard surfaces like sidewalks.
Ive used all the big names, I wouldn't buy anything but Android now, its the most flexible of the OS's, Apple is just too controlling, and some of their built in apps are very limited and they forbid replacements unless you want to jailbreak (safari sucks for example and half the web sites I try need flash). Blackberry is pretty limited and dated and even the new Microsoft phone is still a step behind.