Aikido is often called "Judo at a distance". This is, at least in part, perhaps due to Tomiki. He was one of Kano's judo students. So the story goes, Kano sent Tomiki to O-sensei to learn about this new thing called Aiki-budo. Kano wanted Tomiki to teach it to him so he could see if it might improve his Judo. Tomiki liked Aiki-budo so much that he stayed and developed his own style of Aikido and his own system for teaching it.
I know several shinans who are yudansha in both Judo and Aikido and they all highly recommend Judo as a compliment to Aikido and vice versa.