Favorite Image Viewer?

Which do you like better, IrfanView or XnView? I like XnView's tabbed interface, i.e. browser and multiple images in one window rather than IrfanView's tumbnails and images all in separate windows. However, IrfanView jsut seems easier to use, I dunno.

Currently using IrfanView. I like it, even though it reads thumbnails way slower than ACDSee. I dumped the latter because the program just got bloated more and more. I'll have to give XNView a try, though.