I heard that Aquarion exists/Aquarion Logos is running. If I were to watch all the related series in full, including Aquarion Genesis, Aquarion Evol, etc., where should I start and what order should I watch them all in?
Considering that Aquarion is an original anime (i.e. not based from other sources), it's safe to say that the original broadcast time is the recommended order:
- Genesis of Aquarion (July 2005, 26 episodes): the original story
- Genesis of Aquarion OVA (May & November 2007, 2 episodes) / Genesis of Aquarion: Wings of Genesis movie (September 2007): an alternative retelling of Genesis of Aquarion
- Aquarion Evol (January 2012, 26 episodes): takes place 12000 years after Genesis of Aquarion
- Genesis of Aquarion Evol / Genesis of Aquarion Love OVA (July 2015, 1 episode): featuring a crossover between characters from Genesis of Aquarion and Aquarion Evol
- Aquarion Logos (July 2015, 26 episodes): featuring a new storyline unrelated to the previous 2 series.