Its something I never really thought about, or even noticed. In hindsight, chapters are numbered more often than titled, I guess. Which is obviously easier.
On the other hand, a chapter title can create curiosity if its cleverly phrased. But of course it shouldn't spoiler anything - however it should have some relevance. Yeah... numbers are definatly easier. :)
Oh, yeah--numbers are definitely easier! I do enjoy coming up with chapter titles, though ... which is very strange, considering I hate coming up with book titles.