I don't know, say what you will, but for me it comes down to a few simple things:
1.) Too many irregularities. If there were just a few I could shrug them off, but there's literally hundreds. I won't regurgitate them all, because we all know them by now. There's just too many for my mind to dismiss them all as pure coincidence and/or human error though, which I would have to do in order to believe the official 9/11 story. Not to mention, for some you have to dismiss scientific fact and/or simple reality.
2.) For me at least, motive was far stronger for the US govt. The Bush administration was filled with war mongering neocons, and several of the top ranking officials were part of a group that published PNAC, publicly stating they wanted something like 9/11 so they could further their agenda in the Middle East via military force. For me, that's greater motive than some guys in a cave on the other side of the world hated our freedom.
3.) The investigation was an absolute disgrace from start to finish, and no developed nation in the world would ever contemplate conducting an official investigation in that manner. It was obvious they were covering up, and there are truths they didn't want the public to know about.
4.) The legacy of the Bush administration is one of lies, deceit, evasion, coverups, etc. These people had no problem standing in front of the world community, and lieing right to our faces about the threats we face, and the reasons for war with Iraq. They had no problem kidnapping people off the streets without legal process, torturing them, and holding them indefinitely without charge. Bush is on record saying the US constitution is just a "goddamn piece of paper", and argued the Geneva Convention doesn't apply to his troops. In short, they proved without question in my mind they're capable of an act such as 9/11.
Again, main thing is the irregularities. In order to believe the official 9/11 story, I would have to believe that 500,000 tonnes of steel & concrete imploded at free fall speed with no resistance. I would have to believe that against all engineering odds, WTC7 did the same. I would have to believe that even though the US created, trained, equipped, and financed al-Queda, they had nothing to do with the attacks. I would have to believe that al-Queda just magically got lucky, and picked the same day the US military was conducting war games of the same nature. I would have to believe that people actually called cell phones from 36,000 feet in the air, technology that wasn't even available at in 2001. I would have to dismiss the photographs of diagonally cut steel beams, and the hundreds of eyewitness reports of secondary explosions, etc.
And the list just goes on, and on, and on. Again, it's not two or three things, but hundreds. If the US govt wanted to put this whole 9/11 conspiracy to rest, they could have very easily done so, by doing what was expected of them -- a full, comprehensive, and open investigation. They didn't though. In fact, they did the total opposite.
