Many of us have at least one character (regardless of if we liked them or not) that we think could've been an interesting survivor... these are my options...
Tama[]
It would’ve been awesome to see how Tama would be received by the land of magic since she killed one of the strongest girls they knew and maybe Mao Pam would've offered her to join her school and in the worst scenario Melville would’ve planned to kill her. I think she could befriend Clantail and Mei since they all three have something to do with animals (they could meet during Breakdown). Also, we need someone to carry team Ruler’s legacy.
Lapis Lazuline[]
Although her death is already an important storyline she could do other things like joining Pfle and Shadow Gale’s team in Aces instead of Patricia so nobody would've been killed by Deluge (she wouldn't kill her since she was with Bluebell). She is also a good fighter and could join Snow White’s team later.
Funny Trick[]
The final battle against Pukin was awesome but the deaths were unnecessary and unfair (Kuru-Kuru Hime’s last day alive was her worst). Trick’s magic turnt out to be very useful in the plot like when she found a way to escape from the city, stold Frederica’s ball or even Pukin’s eye. She and Mana could’ve get along since one looks like a Magician and the other one like a Mage, she also had one of the best character developments in the series. Her magic could later improve to become similar to Aya Asagiri’s magic in another Manga named "magical girl site" where the protagonist can also switch things she can't touch like memories.
Weddin[]
Her Magic was overpowered and nobody expected it, imagine she asked Pukin something like ”promise me you won't hurt anybody” and Pukin agrees because she thinks she is making a normal promise but when she tries to hurt someone she can't due to Weddin’s magic. Weddin also had protagonist traits like admiring magical girls and being the leader of her team, we also need someone to carry Namiyama School’s legacy better than our current survivor (not hating on her though). I can see that since her magic was overpowered Asari had to kill her. The worst part is that after her death neither she, Trick nor Captain Grace ever make another appearance in the whole franchise!!!
Filru[]
Zero freelancers survived!!! Both her death and the girl below her were completely unnecessary, to be fair, most of the deaths from Jokers were unnecessary (Umbrain , Kafuria , Uttakatta) but I‘m talking about Filru because her design had some harmony next to the other 4 survivors ’ and because she could've joined either Snow White or Pfle (in other case take revenge on Pfle for both being the reason she got fired and her death) in the events of Aces, Jokers lacked in character development whereas Filru had a lot of it. We can’t keep Lady Proud or Umbrain’s legacy but at least she could keep Kafuria and Uttakatta’s.
Prism Cherry[]
Pythie Frederica needs more allies, I know she has them but since Ripple is now free from her brainwashing Cherry could be her right hand, the best part of it would be that Cherry would be clueless of her mentor’s true colors, she could even fight Snow White and Filru (If she had survived) and it would make sense since they never interacted, but the conflict would get stopped by Deluge who would also be surprised of both Cherry and Filru’s survival, and that would make her recover from her PTSD.
CQ Angel Hamuel []
It was between her, Lethe and Glassianne but since Lethe was very powerful and Glassianne couldn't do more than starring an anime and baking her sweets I chose Hamuel, the main reason she is her is because of her awesome magic that would’ve been useful in many occasions, she seems like a better candidate for a survivor than the Shufflins. Her administration abilities could work for the Human Resources’s head.
Dreamy☆Chelsea[]
This one is short: WHYYYYYYY?????????
I swear there was no need to kill none of the 5 fan-made girls from Breakdown, and in case Asari wanted to kill one of them it should've been either Nephilia or Ren-Ren but not our princess Chelsea. めるさん must be shaking from sadness,