Aerials, aerial cross ups or shield
If you know they are going to attack you then shield>shield grab, also this allows you to punish them if they do one of their dodge actions, all you do is wait and punish accordingly.
If you know they won't attack and will shield then go for more shield pressure instead of grabbing as a mixup. Ex) SH FF one hit nair, SH weak hit knee, (these options also take care of spot dodges which counter grabs) Also cross ups work even better for shield pressure as you can't be shield grabbed. Ex) SH nair (both hits) while landing behind the opponent followed immediately by a buffered turnaround jab would be great shield pressure.
You can also use upB after jab, as it goes through shield. IMO just as good as grab b/c of more damage output and if you miss you can DI away from the opponent and not be punished, although that's very dependent on how fast the other guy is. Still go for grab b/c it's not as punishable as upB and while not as much damage can set up for some psuedo-combos.
Clarification on my question: Can AC dair combo into knee? I have a feeling it doesn't or the opponent can hit you out of it but I need to be sure.