V3 - SmartApps vs Automations— How do you decide which to use?

I’ve been migrating from Classic V2 to New V3. This morning, replaced all my old Routines with Scenes in V3 (what a pain in the neck that is).

In V3, how do I decide whether to use Automations or SmartApps to invoke Scenes? Is there an advantage to one approach over the other? Are there guidelines to help choose one or the other?

If it was a pain, maybe you should have waited for your migration notice so that this was automatically done? Anyway, if you go through the official migration, they get created with the automation creator.
There are currently some limitations compared to Routines in Classic, though. Namely using a mode or device as both a condition and action. And also no way to set a cotnact sensor says open for X time condition. You can read more here.

I’m pretty sure I got an email saying I could switch. But there was no mention of a migration tool.

My question has to do with when do you choose to use “Automations” and when do you choose to use “SmartApps.” Looking for guidance and best practices. The functionality of the two overlaps, but SmartApps seems more capable.

Does one run locally and one run in the cloud?

I’d rather not choose a path that gets deprecated in the next major release.

They all run in the cloud except Smart Lightning. But there’s a chance Automations will migrate to the new Rules API and then run local once it runs local. Groovy SmartApps seem to be slowly fading away, but aren’t deprecated yet.