Happy style hurts my eyes.
Really? Are we talking about the same thing? It's just white and light blue; that's why I like it. Most of the other styles have wildly clashing colors that I find tiring to look at for too long. Plus it uses the green and pink Celebi as thread icons, which I prefer because it's the site's mascot and because it's slightly easier to quickly which threads are new than two different Pokemon. A lot of the other styles are just too hard to read.