Explaining the tabs on the top right hand corner

What types of post get listed in "trending", "hot", "new", "popular", "active", "payout time" and "responses"?

New

This is self-explanatory - the blog posts are listed in order of freshness, with the newest blogs at the top. And of course there is a timer under the post to show how old it is.

Popular

This tab lists posts in order of the number of votes the blog has got, with the most up-voted blogs at the top.

Trending

This tab lists blogs in order of the $$ earnings it has accrued. The highest earning posts are listed at the top.

Active

This tab lists blogs that have new content added, either comment responses, or edits to the main blog posts, with the most recent fresh content at the top.

Responses

This tab lists blog posts in order of the number of comments they have received, with the posts with the most responses at the top.

Payout Time

This tab lists blogs in the order they are about to be paid out. Blogs are paid within 24 hours of being published or being active, whichever is the later. If you click the $$ amount, it should tell you the time to payout. Posts that are about to be paid out are at the top. Curators only get paid if they have voted in the first 24 hours before payment, so it's a useful tab if you want to get in votes before the cutoff time.

Hot

This tab allocates a score to newness, upvotes and $$ earnings, and the posts with the highest total scores are at the top. So a new post that is being upvoted will rank higher than an older post with $$'s that hasn't had a new upvote for a while.

Which one is the most useful?

The default tab on Steemit is the Trending tab - but I find the "Hot" tab the most useful for finding potential good posts to vote for before the whales find them (which is essential to earn a curration award).