I'm reading three of these at the moment, none of them are really grabbing me as reading material.
Redfern's book is a fine overview, but much of it is familiar territory to me.
Vallee/Aubeck book is an important addition to the canon, but it IS a long list of 500 cases with limited commentary. The commentary is very good, but I think the list should have been narrowed down for the lay person. On the other hand, for anybody deeply interested in the history of the subject, I'm glad they DID make such a big list. But as something to read and enjoy, the appeal is a bit limited in my case.
I like Pilkington's book, but I was expecting it to be a more personal book about his interaction with the UFO crowd, and as such a bit of a disappointment as it really spends most of its time rehashing and describing what is mostly familiar territory to me. I really enjoy the first person material in it, but the history is old news, somewhat slanted towards his point of view.
I have not finished any of the three, though, so you can take that with a grain of salt. All of them are good, and in the case of Vallee/Aubeck perhaps even essential, but with the caveats mentioned above.
I did recently enjoy Loren Coleman / Mark Hall's TRUE GIANTS, and was particularly taken by the latest issue of The Anomalist (#14, Electricity of the Mind). If you have interest in the subject matter, both are good, quick reads.