What timeframe is the best for trading?

There are no magical timeframes.  If you have to pay a “spread”, then you do need to increase your timeframe to compensate for the additional spread expense.  A great example of this concept are the Forex and Stock markets.  They both have spreads so I increase my timeframes to at least a 5/15/60 minute time combination.

Other than that, your timeframe is more dependent on your personality than anything else.  I need to know when my price bar will complete and my attention span is typically about 3 minutes.  This is why I use the 3/12/45 minute timeframe.  Perhaps you need more time to analyze the charts.  If so, you would increase the timeframe to allocate the time to analyze your charts before making a decision.

Additionally, if you are using volume and I highly encourage you to do so, then you will want to use time based charts.  The reason is simple — I believe time based charts give you a more accurate picture when reading volume.  Tick charts limit the amount of volume that can be shown in any particular bar, ie after 540 price movements (ticks) a new bar will appear (this will limit the amount of volume that can potentially go into any one bar).