I've been a pretty happy user of mockery [1] for a while, but recently found it getting a lot in my way.
Since mockery uses a lot of interface{} magic, adding arguments or return values to interfaces and regenerating the mocks does not get the compiler to complain about existing, now invalid, usages of the mocks. This means that I have to track them down manually. Or, if I'm brave enough, try my hand at a few crazy regexes that never get the job 100% done.
go-mocky does not use interface{}s, and thus can't hide changes to function signatures from the compiler; whenever a mock has been updated and the function signature has changed, the compiler will complain for all existing tests. This means that I can now catch errors at compile/lint time instead of runtime.
Another added benefit is that the go-mocky mocks are dead simple and very easy to write and maintain by hand, should the need ever arise.