There is no single way to answer this question. This obviously depends on the operator, according to his preference, knowledge, experience, such as what is raised for trade (the financial instrument). Many experienced intermediate traders, especially when trading in the forex market, prefer to use platforms such as MT4 or C-Trader that are primarily designed for exchange operations, such as CFD trading, and for someone with a bit of Commercial market knowledge.
Others, more novice merchants prefer the use of this genre of platforms such as those found from Easy-Forex, iForex, or eToro, where limited math / computational knowledge is required for their employment and are considerably simpler to use.
More advanced / experienced operators, who may also prefer access to multiple markets prefer to use intercessors such as Interactive Brokers or SAXO merchant from Saxo Bank. These platforms tend to contain considerably more advanced graphical / methodical tools (although to be fair most of the analysis tools can also be obtained from MT4 / C-Trader) and also give access to thousands and thousands of instruments including actions , ETF, sectoral approaches to trade, etc; and are designed with the ability to allow merchants to participate effectively in this kind of markets.