In case this helps: The higher end Garmin watches have many strap options, you can try take the supplied strap off and buy a strap made with a different material from Garmin or a third party.
Also, best to take the watch off when showering, dry it completely / wipe down. Put the watch back on once you've dried off also. If your skin is super sensitive, consider taking it off sometimes at night etc.
The rubber band is the one thing that failed on my Garmin watch (and of course it did, it's rubber). I replaced it with a third-party NATO canvas strap and haven't had any further issues. This one has the benefit of more comfort in addition to more durability.
