condenser post list is more compact
When viewing a list of posts (e.g. on the landing page for trending), condenser only shows one line of text from the post after the title, whereas denser frequently shows two lines. This means fewer posts can be seen on the same screen real estate, and it also creates a bunch of whitespace beneath the post image for the listing. From my point of view, the more compact view on condenser looks better. Example screen shots below: