Let's also be clear that these were two very different leadership styles we are talking about. Eisenhower, the World War II commander, believed the President should drive the "middle of the road" and seek to represent all Americans, from both parties, by adopting moderate policies. So his leadership style, while modeled after his days in military command, sought to moderate the influences and policies of the more radical elements of his party at the time, including, eventually, Senator McCarthy.
Kennedy's leadership style was much more hands on, and in a way that would change social policy in the US. To combat segregation and racism, he had to go against many in the traditionally southern Democratic Party and some in his inner circle. Remembered in foreign policy for his handling of the Cuban Missile Crisis, Kennedy tended to be decisive, though not rash. Both he and Eisenhower were consummate students, trying to learn as much as they could about situations, while still acting quickly. They did not make decisions "from their gut" as they say.
I would say that both of these leaders understood the time period in which they were a part. Both Kennedy and Eisenhower completely grasped the fact that they were products of their times and they acted in a manner that reflected this, allowing them to be popular with many of their constituents. Eisenhower understood that the post World War II prosperity of America was his ticket to ensure a content body politic. His policies sought to bank on this prosperity. He was not looking for a problem to fix, as he understood that the period after the war was one where America stood on very solid ground. With such prosperity, the natural inclination was to preach conservative ideology and attempt to maximize its effect. Kennedy was wise enough to understand that the kids during Eisenhower's tenure were now socially active young adults during his. It is in this light that Kennedy was able to use this sense of idealism and tap into it as a reservoir of energy and zeal. Kennedy's vision of a socially democratic nation that was willing to change itself and the world fit very well with the transformative vision of the 1960s. It is in this light that Kennedy governed. He understood that America, in particular its youth, was not asking for conservative "wait and see" on issues of Civil Rights, social equality, or the sense of what can be done. There was an energy present and Kennedy did not resist it, but rather banked on it as a major part of his presidency. Few leaders understood the role of charisma and image as Kennedy did. In a time period when charismatic leaders were becoming more present in America and the world, Kennedy understood how to be the best of them as a leader of a nation that expected it.
Both of these Presidents had natural charisma and charm and a way of making people feel good about themselves. They seemed to always know what to say, how to say it, and when to say it. They were both ex-military men and heroes of World War II and in their day, military men were special and were shown a lot of respect and influence.
Eisenhower is ranked among the top ten best presidents because his term was generally peaceful, prosperous, and because he fought "communism, Korea, and corruption." Quoted from http://en.wikipedia.org/wiki/Dwight_D._Eisenhower. While in office, he enlarged the Social Security program, ended the Korean War, and established the Interstate Highway System. He kept a check on Russia, stepped up our nuclear weapons armament, and expanded the space program. He was seen as a gentleman's gentleman and was soft-spoken, reserved, and refined. Mamie, his wife, was very well-liked and popular.
Kennedy, on the other hand, was flashy, good-looking, and very charming. He had a way with words and was a very good public speaker. He was the first and only Catholic, Irish-American president and the second youngest President to get elected. He is also the only President to be awarded A Pulitzer Prize. Perhaps he's most famous for his cool-headed negotiations during the Cuban Missile Crisis. Also during his administration was the Civil Rights Movement, the beginnings of the Vietnam War, the establishment of the Peace Corps, and the emergence of television as an important media. The country's economy greatly improved during his adminstration. Probably his most famous words were issued in his characteristic drawl, "Ask not what your country can do for you; ask what you can do for your country." Quoted from http://en.wikipedia.org/wiki/John_F._Kennedy. His wife Jackie was considered to be one of the most well-dressed, sophisticated first ladies ever to grace the White House!
In different ways, both of these Presidents forever changed Washington, D.C., the White House, the Presidency, and our country during their lifetimes, and left a legacy that has been unsurpassed by few other Presidents!