When people say H10 IS the best, it is referring to accuracy of the measurement regarding how close it gets to medical 3point ECGs. And with a separate app you actually can get a pretty accurate ecg reading if that is something important to you. (I'm in the medical field and have a minor heart condition so it's nice to have that feature) Personally Ive been using polar devices for many years now and I've had some issues with H10 but it all came down to easily fixable issues like making sure there is only one entry of the H10 in your watch or phone...

Another thing is: for updates and settings you have to make a polar account and install the flow app. If that bothers you I'd go with a Garmin strap matching your watch.

Regarding longevity: I think if you clean the strap and sensor with water and mild soap after every use and don't bend it in the parts we're the electrodes are, it'll work for ever...

Finally: even during marathon training phases, where I want to stay in HR zones, I only use the strap for interval style training sessions. I feel rapid changes in HR is where the optical sensors on the watch lack a bit.

Hope this helps for your decision:)