Depends on whether you mean by weapons or by an ability. For example, Nemea raises it for every 100 kills you get (only needs to be in your party, doesn't need to be doing the killing) and any character will raise it much faster with the Confluence ability on their weapon.
But base, yeah really any character whose weapon racks up the combo gauge fast (hitting multiple enemies with a single attack) will raise it quickly. Also, horseback can help depending on the char. --- "A mind needs books like a sword needs a whetstone." -Tyrion Lannister PSN: gdtarrant