They’re both so bad that it doesn’t matter.
It’s self-fulfilling: it’s the one most retail forex traders use, and they say so, and people think it must be a good idea to use what “most people” are using (that’s part of why “most people” lose).
The three threads linked to above might help you, certainly.
I don’t know, but it’s nonsense. You can use automated trading with MT4, MT5 and dozens of other platforms, too.
Some people use MT4 because it has the most automated gadgets available (they’re called “Expert Advisors”) and that’s another reason why most people lose money.
I recommend TradingView (very good, very powerful, very easy to learn, very intuitive), and NinjaTrader (very good but harder to learn), and SierraChart (technically the best but also one of the most difficult to learn), in that order.
But almost anything is better than MT4 (and MT5).