Other default sort options in folders mode. Currently uses Track number / Track title (don't know where Artist fits in, Album title doesn't matter). An alternative I would like to have available is Album title / track number.
For example, suppose I load 26 files in a folder, 13 of them have album title "The Wall (disc 1)" and are numbered 1 to 13, and the rest have album title "The Wall (disc 2)" numbered 1-13. Currently the default order is to play both track 1s first, in alphabetical order by title, then both track 2s alphabetically by title, and so forth. The suggested alternative would have them default to playing "The Wall (disc 1)" from 1 to 13, followed by "The Wall (disc 2)", 1 to 13.
There are workarounds. My current preferred workaround is to tag-edit disc 2 to make the track numbers 14-26 (in this example). That's not much work for a 2 disc set but could be prohibitive for a 19-disc audiobook. I tried adding an .m3u playlist file to the folder to see if it would use it (no, it didn't in folders mode, though of course you can if you switch to playlist mode).