Hi mad:
Well at this point the choice is endless but my DD does have problems getting attracted by a brightly decorated cover and not paying attention to whether the book's contents would actually be of interest.
My advice is try and work out what genre of book your child enjoys most.
With DD1 it's a good adventure (a tale of daring do); with DD2 it's got to be a tale about a girl
Both girls are better about reading series for some reason.
DD1 - Cressida Cowell How to Train a Dragon (also a cartoon now - nicely done in fact by Disney). - www.amazon.co.uk/Cressida-Cowell/e/B000APSVVK
Lemony Snicket series appeals to both DDs - involves girls so DD2 is happy and an adventure so DD1 is pleased. This was way too hard for the girls to read at first, so I started off reading to them a chapter or two at the weekends (more like an old fashioned serial) - and we're still doing this. www.amazon.co.uk/Lemony-Snicket/e/B001IGQG30 - DH likes that these books aren't sickly sweet or overly sentimental. The girls like that the author always encourages you to stop reading now as what follows is only for those that can handle truly horrible events.
DD2 is wild about greek myths - so we've bought her all sorts of compendiums of greek myths and now she's avidly reading the Goddess Girl Series (a US thing so far, but very good & available through Amazon Books): www.amazon.co.uk/s/?ie=UTF8&keywords=goddess+girls+books&tag=googhydr-21&index=stripbooks&hvadid=25118471334&hvpos=1t1&hvexid=&hvnetw=g&hvrand=2535725078095133462&hvpone=&hvptwo=&hvqmt=b&hvdev=c&ref=pd_sl_4msbp1hr2q_b - basically before they were grown up goddesses, goddesses like Athena and Aphrodite went to high school. Designed for reading age of ages 8 - 12.
Of course the Harry Potter books are brilliant - but also good to have your child read with you so that they pick up on the word play - Diagon Alley - said quickly is diagonally - which later becomes an issue for Harry when using the flue. And useful to discuss meaning of words/ origins of words - just as an example: www.proteacher.net/discussions/showthread.php?t=344576.
If you're running short of ideas have a look at various reading lists - because a diet of high quality children's fiction:
Guardian classic children's library ages 8 - 11: www.theguardian.com/books/2000/mar/24/childrens.library
Book Trust recommendations for ages 8 - 11: www.theguardian.com/books/2000/mar/24/childrens.library
11+ recommendations (these are often more challenging reading but great reads): www.elevenplusexams.co.uk/advice/english/reading-list
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Finally - I think it is important to let your child feel free to try and book and then decide it isn't for them. Too often children feel they HAVE TO read the entire book when they discover fairly swiftly it's too hard/ boring/ not their thing and would rather read something else. My DDs were guilty of not changing library books for ages because they'd made a bad selection but didn't have the confidence to just admit it and get on to reading a better book, so sort of sat in limbo for weeks until I ordered them to turn the book in for something better.
HTH