This one is easy. Legal profession Lawyer/Solicitor.
The job of the legal profession like this is not to find the truth but to defend or to prosecute. The argument is what is in question here, not the truth, The one who tells the most convincing story will win. In theory this should be the truth that will win out.
History has shown us though, the need to find someone guilty can often over ride the truth. The best defence does not mean the truth will be told. The prosecuting party will try to subdue or dismiss evidence that may have the accused released. Objections to the introduction of evidence. The case becomes about the person and how we can portray them more so than about the crime committed. The crime committed is no longer the truth sought, A conviction is chased no matter the innocence or guilt of the accused.
Having all of the facts does not mean the truth will be told. Everything above applies again. The case is about the person and how they get portrayed. Opposing parties combat with words to find guilt or not guilt.
Banks come a close second to this and are often behind the creation of law's. Law that will benefit them and impoverish the population. Banks lie cheat and steal all the time. They double charge for the same things and manipulate markets behind closed doors. They use inside information continuously when trading. They do this using the legal system of law. Hide the illegal activities and bear no cost.
Te legal system also involves criminals of all categories. The sheer volume of lies and manipulations in the courts used in argument and not for fact leaves this profession the one which tells most lies.
When i read this question the first answer that pops up almost instantly in my head is journalism. I consider journalists as the greatest gossips of all and in their quest for a great story, can release false and misleading information or half truths. Sometimes, their reports and stories are a complete fat lie and i just wonder how they feel okay with that. With journalists the statement "Things are not often what they seem" does not exist. They are just ready to fire up what ever thing they perceive to be true without proper investigation.
Sometimes, knowing that what they might have is half truth or inconclusive, they go ahead to say they leave it in the hands of the viewers to conclude. The simple question i always ask is: why bring it up if you are not sure of the facts?
So many disputes especially amongst superstars are caused by juicy gossips brought up by journalist and as if that is enough, Journalists go ahead to add fire to the whole thing by always reporting what the other person said about the other back and forth.
An example of misleading information and half truth if not a complete lie promoted by journalists was during the election scandal that took place in my country Cameroon. Journalists propagated the government's false news of an international electoral committee sent to oversee the elections but news later came in from the real organization that they sent no committee and that they had no idea who the individuals advertized by journalists on news were. Another case was during the civil unrest in the country, when there was instability in two regions of the country yet they journalists kept saying that the country was very peaceful.
The truth is, often at times, journalists are used by the government and higher powers to propagate false information or half truths that are misleading.
Easily it is the profession where you need to over-communicate with people, convince them to accept, control or sway opinions.
I can think of 3 professions where you need to 'SELL' things laced with 'misleading info'.
I won't paint everyone the same but these professions require people to add 'more' information to sell or win. Often, this 'more' info is misleading/lie/half-truth.
Lawyers are most who use this 'power of misleading' others to win case on their side. It may happen even after knowing the truth but they still defend their clients. They will pick polished truths which will shine and make the mistakes dimmer. In reality, our laws have been designed in such a way that everyone can be convicted at any point of time and same time everyone can be acquitted. Yes, it is confusing but that's how the legal system work. We have law to punish anyone, doesn't matter how big or small is the issue. So lawyers use this opportunity to support or defend their client by misleading info.
Lawyers and people in legal system have made the 'legal process' complex so that common public should not be able to decipher the intricacy of legal system. This will not change in near future. System and process will stay, only the individuals can make difference.
Doesn't mean all the lawyers practise this but few of them use this as strategy to win cases. Hope we don't get into these traps of court and lawyers.
If you notice i haven't included politicians in the above list because I'm in India :)
I would go with media as it's already proven hah