Qui-Gon Jinn is an old character that had fallen out of favor, only to have new life breathed into him between the addition of zeta abilities and new Jedi.
QGJ acts a modest attacker with some utility thanks to his dispel ability. His damage used to be potent, but power creep in attacker damage output has killed this. QGJ is now mostly only used for his leadership ability and sometimes for his dispel.
Jedi allies have +30 Speed, gain Offense equal to 3 times their Speed, and gain Foresight for 2 turns at the start of each encounter and whenever any unit is defeated.
Bluntly put, QGJ is still only a relevant character because of his leadership. However, this leadership ability is one of the best leaderships in the meta right now, enough to make an otherwise mediocre character not only viable but a key component of a top-tier team.
The speed bonus is crucial. This adds a massive amount of effective TM to your team (or at least your Jedis) and can keep pace with other TM leads like Rex or Darth Maul. The Offense bonus is notable, ending up at ~20% extra damage. As Jedi are rather weak attackers in general, this Offense boost is quite welcome. Finally, the Foresight boon is exceptionally useful as well, particularly against the AI. Automatically dodging attacks is simply fantastic, and regaining it regularly is a great boon.
While the correct way to use QGJ in arena is as a leader, he can still find some use in non-top teams. He previously was one of the best available dispellers for F2P players. However, thanks to many new characters being released with dispels and characters like B2 and Sun Fac becoming F2P, this use has faded.
That being said, a dispeller is still a key need in arena teams, and QGJ technically does it. If particularly pressed for resources, QGJ is the cheapest dispeller to acquire (especially compared to B2 or Sun Fac) and is simple to gear. He also provides a decent damage boost to the team, whereas most other dispellers are pitiful in damage output.
Stating the obvious, but QGJ’s synergies are primarily with other Jedi when acting as a lead. All Jedi benefit from gaining +30 Speed and tons of Foresight. The Offense boost is also nice, though the difference in boost between a slower and faster Jedi is minimal. This means that you should focus on adding the best Jedi to the team, even if their slower speed means they will receive less of an Offense boost.
Unfortunately, QGJ only brings a single-target dispel to the board, so that leaves the other four slots on the team to cover the other important roles – damage, cleanse, and taunt. General Kenobi fortunately brings all three of those, and is the true backbone of the team.
From there, viable options include Ezra, Jedi Knight Anakin, Yoda, Aayla, and R2D2. Ezra adds another high damage attacker with an additional dispel, something the Jedi desperately need, especially in today’s buff-heavy meta. JKA adds significant damage but not much else. Thanks to the anti-crit meta we are currently in, his use is less than it has been requires careful use. Yoda is a fantastic support character, adding a super-fast Tenacity Up and Foresight, but is especially vulnerable and adds minimal damage output. Aayla is a less popular choice lately, but the stun on her basic alongside her damage output and durability make her a viable option that should not be ignored. R2D2 gets an honorable mention thanks to its ability to boost all of the Jedis’ stats as well as stealth the weaker Jedi. It also helps against Darth Maul teams, a particular weakness of the team.
Other lesser choices include common Plug-n-Play (PnP) characters like Darth Nihilus, B2, etc. These characters are less useful for a QGJ team because they do not benefit from the exceptionally powerful leadership. That being said, Yoda and GK can both share some of the benefits with these characters.
Speed is king, as always. In a Jedi team, QGJ should not be relied on as a primary source of damage. Instead, he should be expected to provide a dispel when necessary. Once speed has been prioritized, stats such as offense, crit chance, and crit damage are useful. While not the strongest attacker, QGJ at least can act as a secondary source of damage thanks to his stats and leadership ability.
I would advise against gearing QGJ for survival. In particular, he’s one of the less useful members on the team. This is because his leadership ability continues even after he is defeated. Furthermore, these survival mods are clutch on more important characters, like General Kenobi and Jedi Knight Anakin..