I'd really like to see more %CDR diversity in items.
The reason being that if you try to max cdr, chances are you're going to be buying over the cap and thus feel like you're wasting stats. As it stands, the only item to provide cdr that isn't a multiple of 10 is Ionian Boots of Lucidity at 15% CDR. Every other CDR item has 10% or 20% CDR. Given that masteries provide 5% or 10% cdr (AP champions, 9/0/21 route), I feel it would be a good idea to put in more 15% CDR options or even some 5% CDR options.
Example: a 21/0/9 AP champion wants max CDR and has 5% in the beginning due to masteries. They buy morellonomicon (25%) and DFG (35%) and still have room for 1 more item to max out. Issue is, anymore CDR would be at least half wasted due to the awkward values in items.