Hmm, there are characters and characters.
I'll split it into three categories recurring char, one off and "hormonal response"
For recurring characters
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TOS - Scotty, he seems to get the best one liner, and spouts the most technobabble. I respect engineers.
TNG - Data and Worf. These two square pegs are classic SF elements, by their alien attitudes they are humorously used to explore humanity.
DS9 - Garek, Gul Ducat. These two are devious and honorable gents, they bring a subtle opponent/dangerous ally mix that Klingons never could do by their sheer brutality and ancient chivalry.
VOY - Neelix, comic relief in a very dry serial. EMH, again, like data, an analog, and a comic straight man.
ENT - Malcolm Reed, he seemed to have interesting problems and in a disposable series, was one of the few I almost cared for.
Eye candy/hormonal response.
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TOS -
TNG -
DS9 - Jennifer Sisko, Leeta (Chase Masterson, regular Dabo girl)
VOY - Hmm, drawing a blank, not even 7 of 9, too cliched on sex appeal. There was a girl on the bridge of Voyager, but she got wiped out in episode one.
ENT - Hoshi
Overall favourite character.
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I would almost opt for Ben Sisko, he has the nobility and chivalry of a good captain. He also has enough self doubt to make him human. His weaknesses are always visible, so we are never let down by any collapse, unlike Picard who we are always meant to be shocked by him letting anyone in.
Otherwise it would be Worf or Data (though we shouldn't discount Q or Broccoli.
Don't get me wrong, there were strong and engaging female characters, Dax was an interesting character, Mjr Kira was fiesty, Leeta and Neelix's gal were compassionate. Quarks mother is a very interesting character too. However few of them were written with sustainable qualities. In TOS Uhura was a strong statement, but appeared visually as little more than a telephonist. Deanna Troy "Oh I'm feeling something, but I don't know what", give me a break. Dr Crusher, Mrs Mom and no other direction. Oh, Gaynan (sp), a spiritual counselor and bar keep, an honest Quark. Just none of them stood out. Maybe that is part of TNG's appeal, it was a leveller. Picard was "I'm Mr Proper" and No2 was lust bucket ego man (could have been played by Errol Flynn), so again the human males were as two dimensional as their female counterparts. Maybe that is why Worf and Data shine.