Bought my wife the Mi Band 2 a couple of years ago and it's still going strong now. Battery lasts about a month and she wears it every day. I'm very tempted by the Mi Band 4.
I had the Band 2 for awhile but got rid of it as it just didn't work the way I wanted.
The band 4 works so much better due to the bigger screen.
You can see more on the home screen with many faces to chose from that can have anything you want on (steps, battery life, time, date etc all on the front screen no swiping around) notifications much easier to read as you can see more, music play back via a right swipe.
The brightness is also much better, you can actually see the screen outside in the sun!
This is what mine looks like right now, with notification example (email) + music playback (works on any video/music player with full volume/skip/pause controls).
Excuse the poor image quality, its hard getting in focus pictures of something so close.