For Sophie, her most damaging options for post-GI within the 20 frames and for the re-GI counter is TAS B:4 and delayed TAS B:4, respectively, both dealing 80 damage. However, since TAS B is -10 on block and the JF is hard, it will probably be better to use 66B TAS B which does 4 less damage (76) but is -2 on block and leaves Sophie at her optimal spacing.
Even if you just land the TAS B4 without the JF it does 65 damage which is 3 less than 3B TAS B. Imo 3B TAS B is his her most difficult juggle (other than that silly 66B b2

B:B236B combo). Hitting the JF for TAS B is also very difficult but at least you have a safety net.
Choosing 3B or TAS B is subjective in that you can get 3 different damage values based how close you are in your execution.
3B followups: 28/55/68 (ty suirad)
none (TAS B was too late, facepalm) 20ish damage
236B (botched the timing or the double qcf motion) 55 damage
TAS B (wait a sec then spazz out on the arcade stick) 68 damage
TAS B JF 50/65/80
missed the JF (still not too shabby but gives you shit oki) 50 damage
4 (something you gotta be able to hit consistently) 65 damage
:4 (look like a fucking boss going into the dramatic angle after a GI) 80 damage
As a third option that you guys seem to neglect which I like to call the fast post-GI move Sophie has is 236B for 35/45/55 damage which comes out in 14 frames. You can't actually cover all options within the 20 frame GI window if you want to; you still need to guess which part of that 20 frame range the move will come in. i14 236B and i18-i20 236236B (theoretically it can i15 but in practice it's much slower) or i20 3B is too large a gap to cover.
That was probably more information than a non-sophie main needs but it really seems like her post GI mixups are the strongest in the game once your master TAS B:4. If you have that move in your back pocket Sophie is easily top tier.