I’ll probably not be interested in an iPad mini 7 unless they switch back to the old aspect ratio (and fix the jelly scrolling, of course). The 6 is just too narrow.
I’m also partial to the Touch ID home button, specifically on the iPad mini, because it allows picking it up one-handed while also directly unlocking it.
Lastly, I wasn’t fond about the changed location and orientation-dependence of the volume buttons on the 6.
I had wanted to upgrade from the 4 to the 6, but it was a downgrade in too many aspects, so I upgraded to a 5 instead while they were still available.