Which is better: unified or unique design?

Question

User interface

On the one hand, it is recommended to adhere to the general style of the operating system to make it easier for the user to navigate. On the other hand, an application with a monotonous design looks monotonous against the background of other applications; the style of the external system does not allow emphasizing semantic features. In addition, an application for different operating systems will either look different depending on the platform, or with an alien style when using a single unique design. How to be and what to choose?

Answer 1

the style of the external system does not allow emphasizing semantic features

This is the cant of the one who comes up with the interface.
The inability of your performer does not mean that the instrument is to blame. He's just making excuses.
There are of course exceptions for some specific software.
But that's just the rare exception.
As a rule, there are more than enough standard interface things.

Answer 2

It is necessary to test on the target audience live, it is desirable to record all their actions on camera, and ask them to comment on what is happening, then study these materials and draw conclusions, identifying from what seemed ambiguous for the user of the interface, naturally they need to pay 1 or 2 bananas like a monkey, 1 or 2 bucks))