I had everything in my Dropbox: all my legal documents, my work-related files, my photos from the last 20 years, and things people sent me that I want to look at again when I'm 80… I literally had my life stored in it (and of course locally on two machines and a extra backup disk). I also accessed it almost daily via my phone and uploaded files from my phone.
So, I tested several services in the range of ~100 Euros a year with at least 1,5 Terabytes:
Jottacloud:
Good Desktop Client (Win & Mac)
Very good iOS App
Good service
Pricey (144 Euros for unlimited storage)
Downside for me: it doesn't automatically convert photo uploads from my phone to JPG and doesn't store them in a folder I choose – plus, the price is high.
Filen:
Good Desktop Client (Win & Mac)
Rough iOS App
Good service
Okay price (108 Euros for 2TB)
Downside for me: the rough iOS App didn't have a document upload with a scan function.
Nextcloud:
Good Desktop Client (Win & Mac)
Good iOS App
No dedicated service; it's Open Source, so some tinkering is required since you manage the hosting yourself.
Weird price range (Hetzner, the cheapest host by far, offers either 60 Euros for 1TB or 200 Euros for 5TB, nothing in between).
Downside for me: the price range.
kDrive:
Good Desktop Client (Win & Mac)
Very good iOS App
Amazing service, document editing included, etc.
Amazing price (60 Euros per year for 3TB)
Downside for me: none.
So, I chose kDrive, even though I'd love to use Nextcloud because it's Open Source and you can choose your own host. If I needed less than 1TB, I'd definitely choose Nextcloud.
And it should be said that all the services I tested offer free options with a few Gigabytes, if that's all you need.
If you have at least one system which is always on and online somewhere, you can synchronise files within your own managed ring with syncthing. It does require having enough space on each device for the synced files, but it has its uses. It can also sync specific folders with specific devices, so you could choose to not synchronise all of that ~1.5TB with mobile devices. As an example of how I use it; I sync my mobile's photos folder with my NAS for sorting into the larger Pictures collection once I get to it, then just access that NAS when needed. A secure DynDNS service could give access to that NAS from other locations where required. Best of all; Syncthing is FREE.
I wanted to ask you, does it give access to a whole Nextcloud instance, including apps like Talk (https://nextcloud.com/talk/)? Or is it only file storage?
It should be a complete Nextcloud installation with all preinstalled apps included. Otherwise they would not be allowed to advertise it as a "Nextcloud" installation and would be obliged to remove all branding.
I would like to put a link to the official Nextcloud guidline on that topic but I can't find it
I checked out nextcloud and koofr when switching from Google drive and settled on koofr. In terms of the criteria you outlined above:
Decent desktop client + network drive which appears like a USB key in your file system, super usable
Very good android app
No document editing but you can open everything from the network drive using the editing software on your device and it syncs to the cloud
Nice price (45 euro for 200GB, which is all I need)
Downside: no integrated document suite for editing in the browser but the workaround with the network drive is very straightforward (one click to enable in the desktop client)
I don't need a massive amount of cloud storage, in the terabytes, say, so I've found koofr ideal for my purposes. Another bonus for me is it's a Slovene company so must be GDPR compliant.