I suppose that there are no obvious differences between these two trading platforms. Of course MT5 is much more attractive because it was created after MT4, nevertheless traders always use trading platforms which they really prefer to use. I mean everything depends on what platforms is more convenient for trading activity for a particular trader, or maybe what platforms makes more sense according to trade style and trading strategy. This questions is very individual, everything is up to each trader. I believe that trader shouldn't spend mch time on searching for the best platform actually, because it often doesn't matter.