From an OS / software perspective:
Have a "core" macOS that has none of the apps / integrations are baked in at an OS level.
You install the things you want, how you want - eg iMessage, Mail, and then iCloud if you want to sync it, and Photos etc.
Have a slim, fast, stable OS that I can just turn on and get going with.
From the hardware perspective, I made this comment a little while ago but what I want to be able to choose is:
- Device: Watch, iPhone, iPad, MacBook, iMac, Mac
- Size: Mini, "Normal / Default" (Air), Max
- Processing Power: "Normal / Default", Pro, Ultra
- And maybe storage.
That way I can go and buy a MacBook Pro (13"?), or a MacBook Max Pro (15"), or a MacBook Mini (11"), or a normal iPad Mini Ultra, or an iMac Mini (21"?), or a Watch Pro, or a Mac Max Ultra etc.
Device + Size + Power.
It's kinda there, but not quite.