A5 Journal inserts that don't feel super flimsy?

I've been using MD notebooks for years but I find that my leather journal is just getting a bit too chunky. I've avoided the usual smaller inserts because they always felt really flimsy and I want them to be able to hold up in storage when I'm done with them, but now I'm considering switching. Which ones does everyone use? I need them to be fountain pen friendly and preferably stitched not stapled. I'd prefer dot or grid but would settle for ruled. Thanks.