Check out Badger Publishing/Learning. I'm positive that, a couple of years ago, they did a Full Flight for Girls series (bit like Barrington Stoke but more girl friendly.) Can't find them on there at the moment (can't remember individual titles) but may be worth an email to them.
The Dork Diaries. Perfect. Tom Gates. Graphic novels & similar like Calvin & Hobbes.
Can't believe someone suggested Michael Morpugo, can't believe his stuff is for typical ability at age 7-8.
Dick King Smith. I'm wondering about all those cute kitten-puppy-pony adventure books featuring gangs of girls. Or my hamster-rat-mouse is secretly a space alien spy books with single boy owners & a few of his mates.
Possibly a bit ambitious, but I wonder about Tracey Beaker, 100 mph dog & similar by Jeremy Strong.
Ramona Quimby? The "Operation Bunny" one that is this month's selection here on MN is nice - my DD is 10 and read it easily so that might do. Would Malory Towers and St Clare's (Enid Blyton) be hopelessly childish/out of date? They are such fun and I still read mine now sometimes as "comfort reading" they are engaging, with so many different girl characters to identify with/dislike... There are some modern sequels written by someone else too - they have Blyton name on the cover and "by XYZ" in very teeny letters.
Thanks for that - we definitely have Wimpy Kid and Michael Morpuro, prob still a bit challenging for some of our kids, Barrington Stoke do some good boys books, but there girls ones are mainly aimed at teenagers. To complicate matters they need to be on the Accelerated Reader scheme. Don't know the My Story series - I'll investigate.
As a school librarian, I agree that there's loads for boys in this category but not a lot for the girls. Popular with our low/er-ability girls are the Diary of a Wimpy Kid series (and all the other copy-cats), My Story series, Karen McCombie, Michael Morpurgo, some Sophie McKenzie,etc. I think there's a real gap in the market really. There are just so many aimed at boys because everyone thinks that boys don't like reading and need that extra bit of help. If you look at the publisher websites, most (Raintree, Hodder, etc) do low-ability/high interest series which should appeal to girls as well as boys. If I think of any more, I'll come back.