Character Development
It has been well-documented that Lucas has admitted he was not necessarily focused on character development as a plot point in Star Wars. As a director and storyteller, Lucas was mainly concerned with crafting visually stunning spaceships for the Empire such as Death Star or the Star Destroyer, and for the Rebels such as the Millennium Falcon or the X-Wing Starfighter. Lucas' creativity was by far a masterclass in visionary work that certainly dazzled me now and as a kid.
However, when it comes to character development there isn’t much there for our Star Wars protagonist and antagonist to work with, except in an example with “Return of Jedi”. In "Jedi", Luke (on the side of good) as a trained Jedi, refused the Sith Lord's taunt to get him to embrace his feelings of hate – a catalyst to turn to the Dard Side and become a Sith pupil.
It’s only when Darth Vader (on the side of evil) with the Empire and Emperor Palpatine - tells Luke that he will turn his twin sister Princess Leia to the Dark Side. It’s then that Luke manically attacks Darth Vader (his father) to save Leia. It’s unfortunate we only see glimpses of that kind of character development in the Star Wars franchise.
To be fair to Lucas and Star Wars, Roddenberry had three seasons of TOS to work on character development before the Star Trek movies were written and premiered. However, great character development we did get. For example, in the rich, complex, and hilarious antics of frenemies in Spock (First Officer) and McCoy (Chief Medical Officer); or the charismatic, rules breaking, ladies' man in Captain Kirk; or Scotty (Chief Engineer) - the brilliant engineer you can always count on the find 10% more power from a failing warp core!
Despite Roddenberry’s head start on character development, I will still give Star Trek the edge in character development over Star Wars. Roddenberry's vision for his characters in terms of their development was personal and introspective, mainly delving into his character's internal struggles and ethical dilemmas such as Spock's Vulcan heritage versus human traits and feelings or Kirk's lack of a biological father and his need to win and impress at all costs.
Lucas, in contrast, rarely dealt with his character's internal struggles, aside from Luke's turmoil with his father issues and his feeling of inadequacy. However, Lucas mainly relied on grand sweeping archetypal narratives of good versus evil to move his characters through a story arc that mainly focuses on action/adventure and lightsaber swordplay.
In this case, I will give Star Trek the edge in character development over Star Wars because of the many different individual dynamics between the Starfleet characters, as well as the rich development of backstories and subplots that give more meaning and texture to well-rounded characters.