My issue has always been that Picard seems very Captain-as-King in 'tude, which is very retro and not enlightened 24thcentury at all. Whereas Kirk is not afraid of showing his emotions a lot of the time, so while he has his great quiet powerful moments (Balance of Terror, CHARLIE X), most remember stuff like RISK IS OUR BUSINESS from RtT or, more painfully, SHE'S HUMAN! from requiem.)
Kirk and Sisko (and Janeway even when I was able to watch VOYAGER) seemed military commander-like, whereas Picard vacillated between King and diplomat. The others could incorporate those aspects while still seeming to be in the service, but Picard ... well, suffice to say I'm not a fan.
Q WHO and TAPESTRY and the end of ALL GOOD THINGS show promise at what COULD have been with Picard, but I have always seen him as a missed opportunity. (also kind of wished they HAD let Q serve as their Exec for awhile, because 1st season Riker was such a damned tourist!)