I'm writing some URL rewriting software, and I want to know which URL scheme is preferable from many points of view:
SEO: Some say Google only splits words delimited by dashes which is why blog posts get better SEO than MediaWiki setups, is this true?
Readability: Finally its down to the user, when they see the actual "pretty" URL links in a search engine results page / their bookmarks/favorites store.
I'd feel the Wiki style is easier to read as the underscores appear as spaces, and therefore don't come in the way of grasp reading, and it also looks neater and more formal, and therefore appears more authoritative.
Conclusion? So which is better from the "technical" points of view? (SEO / Indexing), and from the "human" points of view? (readability / friendliness / prettiness)
According to a Google engineer, Matt Cutts, for SEO purposes "my-chemistry-answer" is better than "my_chemistry_answer" which is better than "mychemistryanswer."
See his response to a question at Google Moderator, Ask a Google Engineer: http://moderator.appspot.com/#9/e=c9&t=long-haired-dogs
As for human point-of-view, I can only give my opinion. I tend to prefer "my-chemistry-answer". URLs usually aren't rendered in a fixed-width font, so the hyphen is closer in width to a space than the underscore, so to me it reads more naturally. Also, as a programmer you may be used to seeing underscores because hyphens aren't allowed in identifiers (and therefore it looks better to you), but most people aren't programmers.