Well, how about a review of the ones "in my lifetime".
John Kennedy was hard to understand because of his accent, but he had that charisma that just carried the day. Its a shame the videos of him aren't of better quality.
Lyndon Johnson was a "good old boy" from the old good old boys school, and didn't talk TO people, he talked AT them. His gruff manner wouldn't work today. And, to a point, it didn't work then either. I do remember seeing him on TV in the late sixties, probably just before he left office, but I am not certain of the date.
Richard Nixon was a good speaker. OK, he was funny looking, but, he was fiercely intelligent and very motivated. Today, we expect a president to delegate and keep himself somewhat above the fray. Nixon couldn't do that, he was the ultimate administrator and a control freak, and that may have been his undoing. But, he was a good speaker.
A good example of his grasp of the situation and ability to communicate can be found in his "farewell" to the White House staff: http://www.dailymotion.com/video/x2335ma_richard-nixon-thanks-his-staff-in-his-last-speech-before-leaving-office_news
Gerald Ford was likable, and somewhat self depreciating. It is a shame he's remembered for pardoning "Tricky Dick", and for falling down the stairs of Air Force One. On TV, he was genuine and likable, but did not come off as overly Presidential.
Jimmy Carter was intelligent, and very down-home, but, again, he wasn't presidential. The reason he had been elected was that he HADN'T pardoned Nixon. Carter's chief problem was his unwillingness to make a decision and stand by it. He was evidently uncomfortable with the power the office wields and could not use it, and it showed when he was speaking to the nation. If you look close at Carter in the last year or so of his term, you can see tears in his eyes while he is speaking. That isn't a good sign in a president who is not announcing a national day of mourning.
Ronald Reagan is remembered as the Great Communicator for one very good reason. He was. Remember, Reagan had been reasonably successful on the radio before he was an actor, then later president of the Screen Actor's Guild before he was Governor of California. Reagan had been a Democrat for most of his life before he got fed up with their slow slide to the left, and changed parties. Where LBJ talked AT people, Reagan talked with them, he spoke with charismatic confidence and a sincerity unusual in DC, and it worked.
George H.W. Bush was not a great communicator, and he wasn't much of a politician.He was obviously uncomfortable in front of crowds or cameras, and sometimes it was almost sad to watch. His entire speech making ability was summarized in three words: "read my lips" and it came back to haunt him and cost him the 1992 election.
Bill Clinton was, as has been mentioned, smooth to the point of being slick. He was very smooth on TV, with women, in front of a jury, and so on. Everybody said he'd be a great guy to have over to a cookout, whether or not they liked him as a president. His primary problem was he had trouble conveying the same sincerity Reagan did. Acutely aware of his image and his "legacy", he would say the right things, but you got the impression he was just Saying it, and in the end, it was 'Slick Willy's' playing fast and loose with words that almost cost him his presidency, and is now dogging Mrs. Clinton in her own campaign.
George W. Bush continued the 'not a great communicator' legacy of his family. He was obviously more sincere than Clinton and was/is honest to a fault, and while he was reasonably intelligent, he had trouble saying just about anything in a coherent way. While every modern politician makes a slip now and then in front of cameras, GW was so prone to them some late night comedians actually got tired of showing them and found other stuff to talk about.
Barack Obama brought the same sort of charisma to the office very few before him had. Young and handsome, very polished but without the same sort of 'greasiness' that oozed off Clinton, he was refreshing after the bumbling manner of W. The problems with Obama arose when he began surrounding himself with former Clinton staffers and some who were up front radical agitators from groups that most Americans did not want in positions of authority in DC. It was his perceived smugness in front of the cameras and the way he talked down to the common people toward the end of his first term that began to wear on the base and made the 2012 election come down to a couple of key states and a victory by only four percentage points in the popular vote.
Future Gazing:
The next president, whatever it is, will have to combine some of the polish of Mr. Obama, but have a more open and honest manner that does not come off as falsely superior. One thing they will be running against that was only beginning to be a factor is the social media phenomenon and the way anything can be instantly "viral" and be around the world twice before they even know it got out. They will have to have a staff that is keenly aware of the power of the new medium, and how it can be used, and abused, by anybody with a 'phone' while not appearing to be overly controlling of it.