I love my Oasis though it is a guilty pleasure as I would prefer to be supporting an underdog like Kobo. The Forma looks nice but why would I buy another reader that is roughly the same size and same functionality?
I recommend getting the best reader within your budget and then buying a case for it. Something waterproof for sure. Speaking of Amazon, they do sell insurance and there are companies that provide insurance for just about any device. Just in case you manage to break you reader even with a case