If you have to trade for the short term then m15 is one of the best time frames you can use to trade because this shows the main level for trading and if you have to trade for the long term then you can use hourly charts because they show you long-term trends long. and Depending on the style of trading if you scalper 1 minute 5 minutes is your favorite time frame. if you are a short term trader 15 minits 30 minits is the best choice. I personally trade in 30 Minits or 1 hour Time Frame in most pairs except Eurjpy. for EurJpy I use a 15 minute time frame