def the last one
I'm gonna sound real nit-picky so don't take it personally!!! The major thing wrong with this new format is there are no numbers on the posts so you can't reference old posts.
The problem with the old format is that the columns were so narrow that the third reply to each post got really narrow so a long post took up a lot of vertical space. In this new format, each column is wider and the font is bigger making it easier to read the individual posts. Great! However, in addition to the bigger font, there's more space between each line and each post, so it still takes up quite a bit of vertical space, maybe moreso than in the old format. So I'm not sure if the tradeoff is worth it. However, major thing to fix is the numbering. I don't think we can function properly without it!
Great new layout.