There is no single indicator, or fixed weighting of indicators, that works best in every situation. SMA, EMA, Bollinger Bands, MACD, and Stochastic Oscillators measure different aspects of price behavior.
An SMA or EMA is primarily useful for identifying trends. An EMA gives greater weight to recent prices, so it responds to changes faster than an SMA. Bollinger Bands are useful for examining volatility and how far price has moved relative to a moving average. MACD is generally used for trend and momentum, while a Stochastic Oscillator compares the current price with its recent trading range and can help identify changes in momentum.
The important point is not to simply add more indicators and give each one a subjective weight. Many indicators use the same underlying price data and therefore can provide redundant information.
A better approach is to define a trading rule and test it on historical data. For example, you might use a moving average to identify the overall trend and a momentum indicator to help determine entry or exit points. You can then backtest different parameters and combinations to see how they perform, including transaction costs and out-of-sample data.
So, you generally determine which indicators deserve more importance through the purpose of the strategy and empirical testing, rather than assuming beforehand that one indicator is inherently more reliable than another.
