I'm a total sucker for anything in the Lobster font.
I also like Georgia, Arial, and Tahoma. I use the first one for fancy headers and the second two for general text in a CSS'd thread. I don't mind Segou UI and Verdana; they're nice too, but I use them less often.
I guess I'm the only one who doesn't like Calibri, but that's only because Word starts in that. I still need my homework typed in Times New Roman so just stahp, Word, stahp. >.<
I'd say Calibri and Segoe UI are my favourite fonts. I got used to Calibri over time, as I decided to try a new font in Year 7 rather than Comic Sans MS (which I somehow constantly used for my whole primary school life), but it's a really clean and easy to read font. Segoe UI wad the font I used when I used to crawl MSN back in Year 5, and I still enjoy using it today (mainly for the nostalgia value).