I think OOO, despite it's issues with pacing (Though, that's about it's only problem) was really, really well done. Though, the saving grace of the show was really Date and Ankh, who really did a lot to influence and help the 'null' of Eiji's character who was supposed to be the opposite extreme of Ankh and Date's ambitious and greedy nature. It made the show a lot more interesting and different than any other show we've seen in the past. The show was really about extremes for sure.
I do think the last few episodes of OOO were superior to Double's, with the beach battle to Ankh realizing his humanity as opposed to Philip realizing his inhumanity as a digital being.
But the whole Sonozaki story line of Double was masterfully written and executed. I really can't find any faults from Kirihiko's death, to Weather, to Saeko's betrayal to the fall of everyone last one of them, it's just breathtaking to watch it unfold before us. The Greeds and Maki pale in comparison to the Sonozaki's, but OOO strengths really lied in Ankh, Eiji, Hina, Date and Gotou, while Double was very much so about everyone.
Double really was a game-changer for sure. Sort of like how Kuuga set the tone for the first few shows of the 2000, I think Double really set a new standard for rider and its possibilities.
I just really like both shows a lot haha.