Hi,
In all honesty I do not know which to recommend. Both are of a similar distance, Cotswold is 102 miles and the Cleveland 109 miles. Whichever you choose I would be sure that you would enjoy. If anything tipped the balance one way or the other I would say that the first 60 miles of the Cleveland being on heather moorland would not be as preferable as the overall beauty of the Cotswold.
After the first 60 miles of the Cleveland you are on coastal while the Cotswold is nowhere near the sea and doesn't have the heather. Much as I enjoy moorland I just feel that 4/5 days solid is not quite so enjoyable as what would be encountered on the Cotswold. Your choice, you cannot go wrong.