the better fundamental traders will surely have an opinion about the market. only the purely technical traders will have no opionion.
The best trader has no "opinion" about the market because he is 100% adaptable, and thus only concerned with the present moment. "Opinions" about the market are not how the best traders makes money, I would imagine, and would only be pursued by them for entertainment value.
As a function of extracting profits consistently, such as a daytrader does, perhaps the best I've met in fact due have an opinion. Their opinions are secondary to the reality of daily droning for dollars. They merely follow the trend in the time frame they trade. They make a good living daytrading futures and options. Heavy speculators at the top of their game do in fact have an opinion and they place their bets accordingly sometimes stacking contracts but hedging their risk. They're not terribly concerned with the drawdown because they have a plan and have off set their risk. This is often more specialized and if wrong the losses can be devastating but several home runs and they are set. Position traders most definetly have an opinion and like the speculator employ several methods that may consist of a blend of fundamental and technical analysis with multiple strategies over various timeframes. I think from my observations the best and most non bias is the hybrid traders who just go with the flow but have the foresight to fire-up the leverage at the appropriate times. Their experience keeps them in the optimum time frames and they are literally in the market at all times. Expanding and contracting timeframes and leverage on the fly. Takes alot of discipline and experience. Partially automated, they become the market.
The question is too broad. What style ? One of our current presidential candidates made 100k starting with 1k and when pressed how she could make such outrageous returns when pros are turning in low two digits she said she read the WSJ daily. For a scalper like me it is the best not to have opinions on the market. In some other styles of trading one trades to make daily bread but once or twice a year (when all conditions seem to be right based on one's own experience and background work) one takes on an outsized position. GC