- Ecosystem - especially with family sharing, iCloud, continuity, backup/restore. Everything just works.
- Reliability - my 2010 MacBook's still going strong, and doing everything my mother wants it to.
- Ease of support - Apple stores, warranty repairs are painless (and they went above and beyond during COVID-19 with me)
- Privacy and security - goes without saying nowadays.
- Ease of use - people pick stuff up quickly on Apple devices.
End of the day, ecosystem is what does it for me. I don't want out, I'm happy with everything. HomePod is the device that really "completed" it for me, and it's now central to a lot of things I do with my personal Apple bubble.
I bought my first Mac (a mini) in 2009, and I haven't looked back. I'm really excited about the future that Apple will no doubt have in store for us, it's a pretty cool time to be going through.