Dark chocolate with a high cocoa content, but not too high. I like it at about 60 or 70%. The Lindt stuff that's 80% is a bit bitter for my taste. I also prefer my chocolate to be fair trade since cocoa production in a lot of places is highly unethical (cocoa beans picked by child slaves). Milk is nice too. I find Cadbury dairy milk kind of a comfort food. I only like white chocolate if it's good quality. Oxfam used to sell some that had ground vanilla beans in it which was the business.
It depends on the quality more than on the type, but in general, I like milk chocolate best. I think my favourite would be Hotel Chocolat's 40%. For fillings, I love berry ganaches and pralines.
Dark.
Good ol' Cadbury's 'Rum & Raisin' I love.
But usually ANY Darrell Lea Dark is great by me, especially Dark Ginger!
Their S/E Liquorice with Dark Chocolate is the most!