Spyderco offers 2 knives that make the choice unnecessary: the Dyad and the Dyad Jr. Both have 2 blades, one fully serrated, one plain edge.
I must admit that I've never carried my large Dyad yet, since virtually never find myself cutting things that require serrations. Of course, have to admit that the first "good" knife I bought, and carried for 18 mos, was the CRKT M16-14, a combo edged knife. Have one other that is a good little utility knife, but rarely carry it -- the Spyderco Walker ltwt.
Now carry only plain edges.