I say 'my new favourite mug', but most of my mugs are in fact my favourite, for some value of favourite.
I have favourite mugs for Ribena and for the first coffee of Saturday morning, as well as mugs which are my favourites for offering to other people.
Some are my favourite because of where I got them or who gave them to me; because they're new or because I've had them since I was at university; because they're posh bone china or because they came from the 99p Store.
Really, I have far too many mugs. I have discovered this because my flatmate is away and thus all mugs are based in the kitchen, rather than up to a dozen of them being somewhere in his bedroom :P
Yet I'm still devastated if I break one.