What do you mean by long?
Well Fairy Tail has been pretty good, a good mix of male and female characters, though the female characters are particulary not all push overs unlike some other simular series or stay on sidelines, well admitedly Lucy doesn't do the combat herself, she is often the voice of reason and is great in her own way. And another main character Erza is pretty awesome, being incredibly strong, loved, a leader, feared (she can make two hot bloodedfighters change tone with just a look) and fun. Well these are just two of the fun characters overall, each character haveing quirks and the show rarely get boreing (rarely will an episode be just one fight).
There is also K-ON!, 4 or 5 girls mostly hanging out and playing music, and of course the characters are fun, though also has a lot of moe, curently coming to an end of it's second and final season. Plot might sound a bit boreing, but the characters are more interesting and will have you enoying yourself.
Hayate the Combat Butler (Hayate no Gotoku) is a favourite of mine, has a male main character, but plenty of interesting female characters, and lets just say that the main character might count at times. It is primarily a parody series so it can be rather fun, playing a sad story for laughs, wacky characters, absurd situations and breaking the 4th wall. And probably the longest I have mentioned, at around 78 episodes. It would ruin the fun if I explained too much.
Oh and if you have not seen it perhaps Azumanga Daioh, rarely much hapends, but the characters (almost all female) are so much fun that it is an incredibly good watch, from hyperactive sometimes cruel Tomo, to the innocent child genious Chiyo, to the quirky airhead Osaka (some on this site think she has AS tendencies). It is about 25 episodes though (maybe not long by some counts), but many including myself cry at the end, not becuase it is sad in nature, but because it actually ends.
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Through dream I travel, at lantern's call
To consume the flames of a kingdom's fall