Here are my opinions, without number rankings:
Kirk - the classic; lets hope the new movie doesnt kill the legend
Picard - smartest, most sophisticated; definitely the Sean Connery James Bond of the Trek franchise (Connery is the best Bond HANDS DOWN! nuff said)
Sisko - absolute coolest; like Mace Windu was the baddest ass Jedi Master
Janeway - best ta tas

but too damn liberal
Archer - best dog, biggest creeper doc; hottest first officer and communications officer
Harriman - victim of poor dialogue and obligatory 'lets make Kirk look heroic and any other Federation officer look like a buffoon" scriptwriting
Garrett - kicked ass heroism for 1 appearance
Pike - wife loves Jeffery Hunter's blue eyes; gets extra points for making time with the original Orion slave girl
April - deserves more than an animated episode; when I heard the Enterprise concept, I hoped the series would focus on his career.