I had never used anything besides the 12" iBook/12" PowerBook and I always preferred the iBook, despite the better specs on the PB.  I never noticed a horrible smell coming from any of mine; they did have a distinctive smell even when new, but I wouldn't say it was bad.  I definitely liked the iBook G3 design over the G4 one though (better keyboard feel IMO, better case color being translucent outside/silver inside instead of that awful opaque that turned brown everywhere).

I didn't think any of the iBooks (dual USB and newer) or PowerBooks (Titanium G4 and newer) were easy to take apart.  The iBooks are a nightmare with all those tiny screws and blasted clipped in case parts that always seemed to break even when being super gentle with a spudger.