I'm no expert, but I think you should set your URLs to a path you like and create content that will make the search engines love you. How one does that is beyond me, but really: content is king.

Some say search engines don't like URLs with lots of "&paramA=this&paramB=that", but I personally think that's applying human comfort to machines. Then again the main developer of this blog once tested how search engines would see converting "this is my title" to "this_is_my_title" and "this-is-my-title". It became clear a month or two later that dashes did better than underscores. b2evolution now converts spaces and punctuation in titles to dashes ;)

Still, I'll say if you have URLs the search engines love and no content they will give you less cred than if you have URLs they don't love with content they can index. So content is king. All else is like trying to keep a woman happy: what works today won't be worth a penny tomorrow :D So experiment a bit with what the URL settings allow, pick the one that you feel is the best for your installation, then blog like crazy about stuff you're into. And be a bit patient with how frequently search engines index your site.