If I was getting this I would want something that gave me the less well-known tunes - so, eg, 1, 5, 6, 7, 8, 13, 17, 19, 29 [does it have a tune??], 41, 43, 47, 48, 52.
By contrast, yet another Baa Baa Black Sheep (and that level of well-known-ness) would not have a Unique Selling Point & would put me off (quite a lot).
The other things that put me off massively about nursery-rhyme singalongs is (a) saccharine delivery (specially "sweet" soppy voices) and/or (because it's sometimes both) (b) poppification, with drum-beats and stuff. UGH.
As illustration of what I like, we have a lovely CD of old-time children's rhymes, which has a Run Rabbit from the 1930s, and an Oranges & Lemons which is from an old (possibly 40s?) radio broadcast, complete with extended RP dance-calling voiceover - all lively and characterful and the opposite of soppy.
But it does depend on who you mean your market to be - musically knowledgeable people, or those who need a bit of encouragement to sing to their children: per cookery book analogy, are you aiming at Nigella's readership, or Jamie's?
Though I would say Land of Nursery Rhyme is quite a connoisseurs book itself (being reprint etc.) so I think it would only be appropriate to match the retro feel.