Gnosis is great but often slept on in terms of power. His S2 and S3 are amazing sources of Freeze with little downtime. Even if enemies have Freeze-immunity, his first Talent is still an excellent source of Fragile. Despite his attack range seeming strange if you're not used to it, you'll find that he's able to deal with a large amount of enemies with S2 and S3 once you've gotten used to him a bit. He doesn't shine as much amidst all the DPS 6*s in the current state of Arknights, but you'll be hard-pressed to find an event where Gnosis isn't useful.
Pramanix is...fine, I guess. Shamare is considered better than her in most scenarios, where the other scenarios would be where you'd want RES shred to increase Arts Damage dealt. The problem is that most of the significant sources of Arts Damage in the game already have inherent RES reduction or RES ignore, so Pramanix is widely seen as a waste of a deployment spot these days.
Aurora is unfortunately almost unusable without Gnosis in the squad. Her attack interval isn't short enough for her S2 to consistently Freeze an enemy to deal the extra damage, and her rotation is too quick for Kjera to be a reliable partner to assist her.
I'd say Gnosis alone is worth pulling for, because he is quite unique among all the 6*s in the game, and he has a great mix of crowd control, support, and DPS in his kit. The problem is the future banner lineup is so heavily stacked in terms of power, that unless you specifically like Gnosis or have a fairly large amount of pulls currently, I'd advise you to save for future banners instead.
Gnosis is also very good in Integrated Strategies, because with a bit of attack speed or a debuff duration collectible, he can freeze enemies just with his auto attacks, and freeze brings those irritating low-altitude hovering enemies to the ground, just like a stun. He's also great in SSS.
Like he's been the answer to several events recently, like a complete monster.
And then as soon as the event is done he just kindof disappears.
I feel like he's kindof like Lappland where if the mechanics are to his favor he can make your life ridiculously easier, just he's not quite as helpful when the freeze isn't a thing (whereas Lappland is still a very effective lord guard without the silence factor)