traders should choose the currency pair which is more appropriate to the concept of trading that will be used , if love doing scalping should choose the broker which allows trading concept such as this.
The favorite ones are major currency pairs, these are pairs which include US dollar, because I am convinced that the high liquidity of these pairs can help traders to boost their account, even if they are lack of experience in trading.
Sometimes, when I am in high spirits, I can trade cross currency pairs, which include all the major currencies despite US dollar, for example gbp/eur or jpy/gbp. Basically, all the combinations.
Crazy traders prefer trading low liquidity pairs, exotic ones, for example gbp/brl. Omg, I can't imagine that I would pick this pair as my primary one. Stressful enough I think, but some traders are succeeded.