TL;DR

Circa 2025, Buying a phone for 4 years use,

for normal EAM/CMMS use we'd recommend 128-256GB of memory,
AI offline will require the higher memory.
If you use GIS you'll likely need 256-512GB, largely depending on how many maps you want to cache.

Details:

The OS and pre-installed apps will take almost 30-60 GB of memory. So if you have 128 GB of memory - that leaves you at least 60 free. If you have 256 that leaves you with about 200 free.

Note if you have an older iPhone or Android, most of the older ones took a lot more space for the OS.

If you are not doing Mapping/GIS in MCe, and you don't have a lot of images, audio files and videos stored on your device and you don't do a 'lot' of other things, a 128 GB phone will work perfectly for most of our users

Things that will require more memory

Onboard AI
MCe with GIS/Mapping
AI models
Photos (high res)/Videos (high res)/Audio

Rule of thumb:

25 Gig free for MCe without GIS/Mapping, so a 128Gig phone with only a 100 or so images/videos stored at a time on the device minimum 100 Gig free for MCe with GIS/Mapping, so a 256Gig phone with only 1000 or so images/videos stored at one time on the device

Onboard AI may increase this - but obviously if your phone doesn't have onboard AI capability, it doesn't apply to your phone and most models with AI naturally come with more memory.