Ive got the samsung galaxy watch 5. The watch SOS button seems to work ok or though I've ever used it by accident. I got one because I have to be contactable as much as possible. I had the galaxy 3 before which with the rotating bevel was better for water use as you could answer calls in the water lock mode. I can't vouch for the different apps except that it logs sessions with Strava quite well. Mind you I use that more to piss my friends in the UK off rather than see how good or bad I actually am.
I'm not sure I'd get one just for this purpose but if it suits you in other ways then go for it. They're great for running and if you go for a swim you can use the watch to buy a coffee after. Make you feel like Dick Tracy though!
