I completely agree regarding Trezor having the most proven record, the best interface, and interoperability with accounting/tax tools. But if I recall correctly, the Trezor team simply walked away from the ZEC integration and said that they were not interested at all in adding shielded ZEC then or in the indefinite future. My impression was that they slammed the door shut behind them pretty hard, though to be honest I have no idea why.
Maybe if we all yell at them on social media they’ll change their mind?