Anime that needs a new season

[Dark Dragon]

FMP: Yes
Bacanno/Durarara: I would say yes, but it feel like they finished the story. I'd rather see some new materials.
Claymore: Either a reboot or they need to retcon the last 3 episodes of the anime.
D. Gray Man: Wait till the manga finish imo.
F S/N: Fate Hollow Ataraxia please!
HSDK: 2nd Season could end after that next story arc, would be perfect.
Hunter X Hunter: I think Togashi currently exist only as a floating head. I can see it happening when the ant arc ends sometime in the next 10 years.
Soul Eater: Retcon and the manga isn't far enough head for a second season.
Berserk: I would say wait till the manga finish.
Hajime no Ippo: 100x yes this is one manga that has enough content for several more seasons.
Moyasimon: Yes!
Gantz: I think the manga story got really stupid, but to each his own.
Guin Saga: yes please!
Kaze no Stigma: ditto.
Skip Beat: definitely!
Air Gear: I might be alone in this but i think "Oh Great!" is good at setting the premise and then proceed to completely and utterly rape the story. I feel like fan of the anime Air Gear would despise where the manga story is right now, but that's just me.
Isekai no Seikishi Monogatari: I feel like this series sets itself up for a sequel so it's likely that might be Kajishima sensei next project.

The #1 anime on my list that i feel deserve a new season is Mahou Sensei Negima. This series really need a proper anime adaptation that doesn't butcher the story.

Rurouni Kenshin: I'd kill to see the last story arc animated.
Great Teacher Onizuka: They can do Shonan 14 days and then lead it into the final manga story arc.

[Idealistic]

Kekkaishi.