It sounds like your dad is either one of Jehovah's Witlesses or is studying to become one. True, the official site looks like the truth. That is because they have one specious argument to back up another, and it is such an intricate web of lies that it sounds like the truth. One of those lies is that those other web sites are all lies.
One cannot possibly form a valid, objective opinion about anything if all the sources you are going to use are controlled by the same organization. This applies equally with politics. If there is a diversity of sources, a good politician (that is, one that is honest) has a good chance. But, if all the media are owned by special interests, the same good candidate would be shot down by those interests that would suffer if they got in. This is equally true with the Watchtower Society.
The real truth is that all those apostate web sites are written up by people that have been there. They have tested the product and been through it, and have found it Not Acceptable. The Bible itself has been tampered with, as those apostates will attest to (compare the King James version, which was written by a group bent on making the Bible readily available, with the New World Translation which was written by a cult bent on supporting its own doctrines). The apostates also expose the true origins of the cult, the reversals of doctrine, and some of the dirty secrets about the UN and pedophile scandals. They also expose the fallacies of living the Watchtower way of life.
And, of course, the Watchtower Society doesn't want you to know that. Would a drug company with a diabetes management drug (and a huge profit on that drug) want a cure for diabetes to be exposed? Or, what about GM wanting a candidate that would allow 10,000 competitors to flood the market with better cars and put GM out of business? Those people don't want you to know the alternatives (and most people get flyers in the mail about these issues). The Watchtower Society is no different. They don't want you to know about their history, or that 1975 was actually predicted as the end of this system, or that they support pedophiles and silence the victims, or that Christmas is supposed to be celebrated (Luke 2:10-14), or that nowhere in the Bible is there scriptures where Jesus ever went door to door or reported field circus activity, or that 6 year olds are supposed to get baptized, or a whole lot of other things.
Keep reading this forum. Most of the people here were once Jehovah's Witlesses and know what went on in that organization. Pay attention to personal experiences--the diversity therein shoots holes in the "unity" myth. Feel free to read other literature against the Watchtower Society, such as Crisis of Conscience. Feel free to browse the other apostate web sites. And, I challenge you to find just one pro-JW Web site that was written by a JW, which has nothing but praise for the organization, and was not written by the Watchtower Society itself. You are not going to find such.