most important characters

I have to say that I am not entirely sure what the answer to the question is...

Although cutting it down to 5 is a bit steep. I really dont think that limiting it so much is actually possible.

Kirk may have saved Earth and the Federation on several occasions, but would have done so without the Trinity or the rest of his crew??? At the very minimum, a vote for Kirk, also has to include Spock and McCoy, and is really 3 votes.

Meanwhile Sisko may only have saved the Federation and Bajor, but you should remember that the Prophets weaved the entire universe around him, to ensure he would be in the right place at the right time... You cannot get much more important to the universe than that even if the universe doesn't know it...

I think the Zephram Cochrane would have to be there (at least from an Earth Point of View), and possibly Boothby, without whose guidance half the Starfleet Officers passing through academy (including our heroes) may have made some bad choices that would have affected where they go...

So I can get it down to 6. With justifications for them all... And I think the reasons why they are important is an equal part of this... And that before we start going through the other scientists and politicians that changed the universe around them (thus showing their importance)

Richard Daystom - AI and Duotronics.
Dr Noonian Soong - Positronics, and all his android children.
Dax - Curzons diplomacy, Jadzia presence at Siskos side.
Edith Keeler - and we all know why she was so important...

This list could go on and on.