There is no one-size-fits-all answer to this question. Tick charts show four candles per bar, which gives an updated view of the market from different angles and better represents the volatility in prices with minimal effort to interpret. The dark tick chart lags behind the lighter, time tick chart in order to give users more information on the current state of the market. The tick chart is a lower resolution view of price movement, so it can be difficult to discern small changes in price. However, there are pros and cons to both chart types - it ultimately depends on what you are looking for as a trader.