Even though I consider it unproductive, I'll play along
@
ammarmar
I mostly agree with your post. But I wouldn't say Vilgerfortz was considered to be by far the most powerful sorcerer alive. I like to see him more as a brilliant mastermind, while he was no doubt one of the most powerful mages.
I suppose that power, although it depends on the talent and work, mostly comes with experience and age.
In terms of power, I think Tissaia de Vries would be one of the few who could be considered really, really powerful. She was an Archmage, one of the most respected sorcerers alive and probably most respected at Aretuza where she was a rectoress before Rita succeeded her. She was a teacher of many famous mages including Yennefer and Phillipa. During the Thanned coup she more or less by herself stopped everything and started interrogating everyone. After that she lifted the whole magical blockade with a single spell (something which Keira never saw in her life) and then retreated because she was neutral. Tissaia was also one of the few mages who conducted examinations on the elder blood gene long ago (Francesca was added later because she was young at the time). Among those mages was also Hen Gedymdeith, the oldest sorcerer alive, but there is not much information about him. The reason we don't see much more of Tissaia's power is supposedly because she wanted to remain neutral.
Phillipa was also very powerful, probably at the same level as Vilgerfortz if not more powerful. She was one of the leaders during the coup. Also, Tissaia said that Phillipa was one of her most talented students. She was one of the few to have mastered the art of polymorphy. And supposedly she was 300+ years old.
Francesca and Ida are a mystery since not much is revealed about them but since they were old elven mages they were probably very powerful. Francesca's father was an elven sage, from who she inherited some of her talents.
After all we also have Avalach, an elven sage, and quite possibly he was the most powerful one. It depends on how you look at it, is he a sorcerer? I presume one could consider him as such. In the books he doesn't seem much interested in flaunting his power, although there is some of that. But in the W3, Avalach was the one who hid Ciri on the Isle of Mists, he calmed Ciri with a spell at Kaer Morhen, he was the lead one who used the Sunstone, and he created that barrier at the end of the game that Yen could only tear a hole into. I'm not sure if he was responsible for the actual occurrence of the Conjunction of the Spheres. And if we consider the W3, then we would have to mention Caranthir also. Caranthir was probably one of the most important factors of the Wild Hunt's power.
But Tissaia, Avalach or Vilgerfortz were not members of the lodge so this might even be considered off-topic. As far as the Lodge is concerned I would say - Phillipa, Sheala and Francesca were the most powerful members. Maybe Ida too, but there is not enough information.
Again the inconsistencies... Why would the lodge send Keira and Sabrina, supposedly young and inexperienced sorceresses, to capture Vilgerfortz in his castle? From what we have seen Vilgerforz would have obliterated them without problems. It doesn't make sense. It would be more appropriate for Sheala or Phillipa (or both) to go.
