The cases by Eastpak are good. Very well made. I’ve been using the XL version. It costs a little more than the standard size but also holds a huge amount of stuff without deforming.
The three loops in the top can hold fountain pens you don’t want to get scratched in the main part of the case. There’s a divider which completely protects them. There are no “fiddly bits” in these cases. Everything is a useful size. Spare Lamy nibs and cartridges fit in the small zipper compartment but are still easy to access
Maybe the standard size is large enough for a few pencils, a sharpener and erasers.
I find the solid cases much easier to access than the floppy cases.