For something specific, FIVE. Which is a taste thing I guess. R'n'RC was also a massive disappointment, she came to London, had such a great concept - and yeah, the booklet was amazing - but overall the music was pretty dull.
Also, her 10th Anniversary. GUILTY is her album that I dislike the most, AT08 is one of her worst tours in my opinion and A COMPLETE was cool, but with how close A BEST II was it all stunk of Avex cash cowing.