This is a very subjective subject.
I happen to like both. Each has its place. But I would create 3 catagories. Plain edge, combo edge, fully serrated edge. Combo edge on a short blade is not all that useful but a 2 inch serrated section on a 7" fixed blade can be very handy. Also, for awsome self defense, a fully serrated Spyderco Military is hard to beat. It can slice through heavy denim or leather jackets/gloves like they weren't even there. I love mine for SD.
I find serrated edges need to be sharpened only about 1/10 the amount of a plain edge. However, serrated edges suck if one needs to do pressure cuts (i.e. cut up boxes) or any kind of carving.
We have a serrated kitchen knife (very small serrations) that gets used on a daily basis. We've had it for about 15 years and it has NEVER been sharpened. It's amazing. The handle is even starting to come apart.
So, while I tend to lean toward a nice, sharp plain edge knife, I still see the need for serrations and even combo blades on occasion.
Regards