I have an iPhone, iPad and AirPods but I’ve never used an Apple Watch. My main uses at least at first would be to monitor heart rate when exercising and record lifting routines at the gym via Strong app. I use my iPhone at the gym now and find it a hassle to take in and out of my pocket to record reps. I’ve been looking at used Series 4 and later or possibly a new SE. I think I’ve read Series 4 and later will have similar heart rate tracking. I think I would like the Always On display which I don’t think the SE has.
Any recommendations for my scenario? I also ideally want it to last at least a few years
Apple Watch upgrades are very incremental. If you buy a new one you'll very likely get software updates for longer. So I'd buy the cheapest new one you want too afford.
The always on display may not be necessary. It's mostly useful for glancing at the watch without touching it before.
It seems like a new SE is probably the way to go then. I looked at the Series 8 a bit and it looked like the main difference for me would be the Always On display but maybe I don’t need that.
I have the last gen SE which was several years old at that point and still today it does just about everything you’d need it to do. The new SE should be a big improvement and should be all you’ll need for years to come.