I've used rubber straps for years and in my experience the best of the lot (and I include Isofrane) is the Christopher Ward Hybrid rubber. It's thick yet supple and incredibly comfortable out the packet. At £60 it's not the cheapest but also not the most expensive considering its quality. The buckle is beautifully made (unlike the Iso that's sharp) and finished too.

It's this one:

https://www.christopherward.com/stra...SXK-DC-ST.html