In my eyes, the less stamps the better.
More stamps mean having to get a new passport (or additional pages), often at a cost (either time, money, hassle, or all three).
Additionally, more stamps give customs officers more reason to take their time as they review your passport (reading more stamps), asking more stupid questions (why were you in XXX country only two days?), etc.
I used to want to have more stamps for bragging rights. Now, if I want to share with my friends/family which countries I visited, I'll show them pictures, souvenirs, etc.
Thankfully, I also have an EU passport (besides my US one). No worries about stamps in that one (when crossing from one EU country into another). I must have used that passport at least a dozen times since I got it, it still does not bear a SINGLE stamp!!!
