There's little content available for the middle school age group that just a good read. Great to see wimpy kid, but the amount of tween fiction, especially fantasy, is low. The Wings of Fire release was precisely the kind of thing we need more of, but it's interspersed with a lot of stuff that this age group just don't like.
I'm seeing too much stuff tied in with commercial products (i.e. Disney/Pixar tie-ins) and not enough decent story content for these older kids. If I look at the selection for 9+ it's a ton of Disney stuff which is basically merch; stuff that's not popular even if parent have fond memories (looking at you Enid, Roald, C.S); heavily overpriced Harry Potter and a handful of relevant stuff for young teens.
There are so many popular authors for this age range. Please stop with "Elsa buys some Frozen merch" (I'm not going to buy stuff that is some generic story written to order to peddle a trademark) and "50 stories your grandma used to enjoy". More stuff for this age group from series that are popular and relevant please