Futuristic? Check, Awesome? Check, Derpy protagonists? Check, Awesome female protagonists? Check, Rival childhood friends? Check, Awesome seiyuu? Check!! What else is there to list? Both animes are friggin amazing they even have same same seiyuu and both have ass kickin' OSTs what are you waiting for go watch it NOW!
Futuristic? Check, Awesome? Check, Derpy protagonists? Check, Awesome female protagonists? Check, Rival childhood friends? Check, Awesome seiyuu? Check!! What else is there to list?
Most of the seiyyuu are the same as well~
Accel World and Guilty Crown are both action anime that take place in a futuristic setting and have the same kind of feeling to them. Both series contain male protagonists that are weak and crybabies at the beginning of the story. After meeting the main female characters which are beautiful, popular and out of their league, the leads decide to become stronger in order to meet their expectations or protect them from harm. Both anime also offer superb animation and incredible fights between the characters. If you enjoyed watching one of them then you should definitely check out the other.
The character relationship are similar. Ouma and Haru are voiced by Yuki Kaji, as an individual with no confidence, thinking that they can do nothing, they both meet a girl (Inori in Guilty Crown and Kuroyukihime) and see a whole new "world" about what they can actually do.
Just that Accel World had a much better story planning.
Main Similarity is the Characters :
Both has that one main girl protagonist who is awesome and powerfull , one that every anime should take a note of , and of course that one main male protagonist who is a retarded coward and a crybaby who should not waste the air that girl breaths :P Guilty crowns main character is a bit better than the fat short guy though .
You want some awesome and extreamely rare romantic/action animes that can bring the both genres perfectly and equally ? Well , it looks like impossible in this century , since they always find a way to
Both series contain that Sci-fi theme involving battle. I find a small resemblance between the Endlave in Guilty Crown similar to the Duel Avatars in Accel World in which both are human battle avatars/mechs. Romance in both series are also imminent.
Both feature some sort of weakling hero with a beautiful well-known heroine
Both also have some sort of fighting aspect to them
Since Guilty Crown, the only thing that I know from this anime is all about character which Yuki Kaji's speciality: a nerd/solitary/loser person, but smart (Shu and Haruyuki). But his life changed after he met with a popular girl (Inori and Kuroyukihime), so he also caught up in the problems experienced by the girl itself.
Taking place in a near-future Japan, a weak-willed protagonist meets a girl who changes his life forever. Both Shu and Haru share the same VA.
Guilty Crown and Accel World share a few key elements.
First and foremost, the main protagonists of both series start out as wimpy losers, but are then given the opportunity by a girl to harness a power they never imagined could exist.
In both the main protagonist reacts a certain way to the power/opportunity at first, but later goes through major personality changes.
Both anime have a high school setting.
Both anime contain somewhat emotionless female leads.
There are more similarities, but I don't want to throw out any spoilers.
Using the template of a Character that start from dust and become a overpower hero, those story focus on a Main Character with very little trust in themselves, that need to overcome this psychological wall, attain from a different reality brought to them, in order to attain their goal. Romance, Sci-Fi, Drama focused. I recommend it to every new people to anime, as these will appear as really entertaining and well made. In my opinion, Staple to the "guide", I'm new to anime.