Biggest day-to-day may be texting w/iPhone users. Samsung uses RCS, which is similar experience to iMessage w/other RCS/Android users. But Apple won't support RCS so you'll loose things like typing status and I believe if you add an emoji to a message the Samsung it is converted to text in iMessage (i.e., "Tom loved ....").
I'm sure there's more but that was the thing a buddy of mine said he missed the most when he made a similar change to Android. You'll also want a Samsung watch to be consistent/integrated - the Watch 6 Classic is the current best IMHO. I've been using Samsung watches for years and quite like them, especially that they look like a normal watch - the square body of the iWatch is really ugly to me.
You can run Google Messages on your laptop in Windows so you'll have access to texts on phone/watch/computer. You can also link up apps and calender, etc., to Windows. I use Apple Music on my Samsung phone and w/Google Home as my default music app (due to getting Apple Music w/my phone account). Works well.
There is an excellent Android only dashboard community app that is really nice if you want to control things from your phone.
I'm not using my watch for HE/device control, so don't have much feedback there.
Moved this to the Lounge as that's probably more appropriate.
