We have ebags Motherload backpacks and love them. Also have the rolling versions that we check. Amazing customer service as well.

The backpacks pack like a suitcase and have very clever storage areas.

I will add that AA and Delta have been brutal about carry-ons lately. Last time we flew delta, gate agents were patrolling the gate area, asking customers to check there bags and questioning the sizes. AA was making people use the bag sizer!