From least to most used:
- mini 4 (wifi 64GB, IOS 14.8): hardly used, since I replaced with my mini 5, but cannot sell it because the battery is dead and instead of selling for $20-30 I keep is as part of the collection
- 10.5 pro (LTE 256GB. IOS 15): replaced by the 11 pro but has the white spot so I cannot sell it for any decent amount (over $100), main use is as a second monitor for my laptop for my university classes (duet display, also used to draw charts for my students via a projector) and as temporary replacement when my other iPads pro are charging, and to beta test iPadOS
- mini 5 (LTE 64 GB, IOS 14.8): mainly used in bed when I wake up, and for travels (I used it much more before Covid, since then it doesn't get much use as I hardly ever use it at home other than in bed)
- Mini 2 (wifi 16GB, IOS 10.3): I have been using it for years for my dance school (my secondary job) for a 32 bit music app for which I found no 64bit replacement. Battery still pretty good. Also for my 32bit games never updates to 64bit. Will stay on IOS 10 forever. Used almost every day since I give classes almost every day. Plan to use it for at least 10 more years
- iPad pro 9.7 (LTE 128, IOS 13.4): replaced pen (pencil 1) and paper for my dance school (payments, lists etc.). Used almost every day just like the mini 2. Since it has my second SIM card, it's also used if I need a cellular iPad on the go (with either smart keyboard or logitech create). Plan to use it until battery holds a decent charge, hopefully another 6-8 years.
- iPad pro 12.9 (2015, IOS 14.8): used on my desk as a sidecar secondary monitor for my M1 mac mini and also as notification device for my secondary accounts (secondary facebook, secondary messenger etc. since IOS cannot have 2 accounts, contrary to Android). Also as a PDF and PPT viewer. Battery was replaced in January. Plan to keep it forever (even when the battery dies in 8-10 years), even if just as a secondary monitor. Used with logitech combo touch keyboard with trackpad, pencil 1 and MOFT stand.
- iPad pro 11 (2018, 1TB, LTE) and iPad pro 12.9 (2018, 256GB, Wifi). Both on 14.8, with Magic Keyboards and pencil 2.
Both my most used iPad at home for videos, remote desktop, reading, replying to messages and everything I don't need a laptop for. Hard to say which one I use more, probably the 12.9.