I['m looking for a watch with sleep detection, fall detection, EKG, heart rate,

For the features you want, Apple Watch Series 8 would the only reasonably priced option. You can buy in Aluminum or Stainless Steel (which costs more but is more durable and has a better Sapphire Screen, plus Cellular capability standard).

Do NOT buy Apple Watch SE as not all of the features you want are available on the SE Model.

Here is a link which lets you compare the models --> Apple Watch - Compare Models - Apple

Yes, the durability between the Aluminum and Stainless models is [to me] significant. And the Stainless Apple Watch comes with cellular capabilities standard, whereas you have to pay extra to get cellular capability on the Aluminum watch.

And you're very welcome. Enjoy your watch when you get it.

I should ask what iPhone model you own? You MUST own an iPhone which is capable of running iOS 16 at a minimum.