I'm still on my 11 but definitely upgrading to the 15 Pro Max and I'm very excited! I'm confident I'm going to notice a fairly big jump! My wife is also still on her 11 she literally doesn't care about phones (or any tech) and would happily keep her 11, she has no reason to upgrade other than the battery being pretty poor now so I could easily just get her battery changed and she'd be happy to keep her 11...but I'm going to upgrade her to a 15 (maybe a pro depending on price difference but she won't care about the feature differences between the standard 15 and pro), purely because then we'll both have USB-C. I couldn't cope with one of us having lightning and one of us have USB-C.
We drive each other's cars (which both need to be plugged in for CarPlay) and although I know we could rely on Magsafe/wireless charging, it would just complicate my life having to carry different cables everywhere.
We can then give our 11's to our two young kids because we bought them Kindle Fire kids last year but they're terrible and I NEED to get the kids in to the apple eco-system so their devices are easier to manage but can't afford over £500 on two iPads!.....I wish apple did an 'iPad Kids' which is just plastic (because it'll go in a silicon case like the kindle fire kids) and has older internals but was priced at something like £199 because I'd pay that just so I can get them into the apple eco-system. It could use a processor from 2 or 3 years ago, same for the camera, it really wouldn't matter but I just need an apple device so I can get them on iCloud and iOS. The Kindle is physically great with the case etc.. and is cheap but the OS and the management of it sucks! So for now, they'll have our iPhone 11's and I might consider getting the batteries replaced.
Eitherway, I am very excited to order a 15 Pro Max for the first time ever!