I used Qubit extensively and think it's easy of use is great and many core centres will recommend Qubit. Quantas looks essentially the same but considering whenever I've used Promega compared to other companies, they usually ended up performing worse (primarily their wizard kits versus the NEB monarch kits), so would go with Qubit over Quantas.

The figures they use are comparing are against the Qubit 3, Qubit 4 has been out a long time it and seems like a dated comparison to look better than they are