Can you give me insight, do you think trading via ETH/BTC is more profitable than ETH/USD? Please give me an advice.
It's all about your analysis honestly. There is no correct answer to this. The pair you'll get a better trading grip on first should be your go to trading pair. ETH/USD is generally easy to trade as you have to trade with the market while ETH/BTC hasn't been that volatile lately as BTC and ETH have too much correlation with each other these days lately. So i think ETH/ USD is naturally better.
^ That is right, it depends on your analysis and of course, it also depends on the market situation.
Most likely, people use stablecoin pair when they saw the market going down and when it will go up they will use high volatile coin pair so that they will generate profit. We cannot say which is more profitable among them because it depends on us how to decide on which pair we use. After all, we have different analyses used in trading. I think I would with a high-risk pair, ETH/BTC would be a great choice.