whether an opinion is popular/unpopular, perhaps especially in trading, depends to a huge degree on context and location
anyway, in the spirit of the thread, i offer two unpopular opinions
the first, below, is doubtless pretty unpopular and maybe even unwelcome here (and would be, maybe, at ForexFactory as well) for quite a few different reasons, but it’s so widely accepted and universally agreed on anywhere else in the trading world that it’s not only completely “popular” but also so generally accepted that it’s not even worth discussing at all anywhere else
and most of the second, below, technically, isn’t really “opinion” at all: it’s just a factual statement
firstly, MT4 is absolutely the world’s worst trading platform, it’s horrible, it’s clunky, it’s unreliable, it displays indicators incorrectly, it’s laughably bad, and it’s also a substantial part of the reason why such a very high proportion of people taking up trading never achieve any success at all worth talking about
secondly, the party that the great majority of people trading spot forex think of as “their broker” actually isn’t a broker at all, according to any sensible or reasonable definition of the word … and this is actually a far, far more significant issue than people realise when they’re part of what seems to them to be a widespread community nearly all of whom collude and agree, mistakenly think of them as “brokers” and both discuss them and deal with them as if they actually were
there you are: i told you they’d be “unpopular” 
PS: and i’m editing this post (the next day) to add that i’ve just said more about my second unpopular opinion HERE