I read this question in a comment and though I had an answer from my own personal preference, I think it would be really helpful for others to make this decision and consequently for theme developers to get a good feel for where and what they should concentrate on if there were some discussion on it.
I personally prefer one column themes with a minimal second column. Most information that is put on my sidebar(s) is extraneous and could be placed elsewhere. I have also found that some of that information deters from the original content of the blog. The landing page concept is nice for search engine traffic where extra links and information on the content might help you draw in the user to explore some more. However, the face of the blog is cleaner and chock full of good stuff to read with lesser distractions.
Do you like one, two or three (or more) column themes and why?