I actually don't have any beef with QuickTime. I haven't seen it steal any associations in a long time. Now about iTunes...
iTunes has this MobileSync folder which it imposes on you on C: drive without ever giving you the choice. So if you are juggling a lot of apps on iPad, the free space on C: really fills up quickly.
Only by digging around did I find a workaround - a symbolic link or alias that points the program to another directory.
(And the App Store sucks. They should really just open it wide to work like Firefox)