I still have a 7-8 year old Powercal (including a nasty chest-sliding crash). I'm on my 3rd strap (I used the original, a polar, and a Garmin premium strap, best of the bunch).
Obvs you can't buy a Powercal anymore, but with that said, look for models that have a screw-style compartment, instead of screwed-on, like the Garmins.
Polar H10 has a pop-top compartment, so maybe that'll work better for you.
Are you just killing the straps? Or the sending units? The manufacturers are obviously cagey about it, but the straps are just electrode units, and can be interchanged...provided the mounting lugs fit your unit.
I've taken to washing the strap every week/so of use. More if it's especially sweaty out. The original strap with hard electrodes was very tolerant of non-washing, but the soft electrode straps start throwing bad readings for me after a couple of weeks.
I'm not personally a fan of the optical sensors. They need to be tighter than I like for them to work well, where the electrode straps can be looser (YMMV, depending on body shape, etc...)