I have both. I like plain edge knives becasue of the looks and ease of sharpening. A serrated blade is good if you are out in the sticks and your knife is getting dull because the serrated part will still retian some cutting power. If I were in the Iraq or some where like that I would carry a serrated blade.
Serrated blades do not find their way into my collection simply because I have no use for that edge. I'm sure I would own one if I worked in an environment where cutting heavy duty plastics or ropes etc was an every day task... But as it stands such is not the case. I have always thought that maintenance sharpening on a serrated blade to require too much effort just to own one for every day use- a plain edge is all I need:)
I prefer a plain edge. Mostly for the ease of sharpening than anything else. I do own a couple of partially serrated knives and the serrations have come in handy a couple of times, but blades that have the whole cutting edge serrated, no thanks.
i prefer plain in any situation, even where a serrated blade would be superior, because they are much easier to sharpen and keep sharp. though i would definitely take a full serrated over a combo edge. combo edges usually dont provide enough of either type of edge to be productive in most situations IMO
I have some combination blades & a couple of fully serrated ones, but the majority of my knifes are plain edge. For me they cut better & are easier to maintain. I don't cut much rope & for cords, seatbelts, woodcarving, a plain edge is the only way to go. If something needs to be sawn, I have a pocket saw & a small bowsaw. To each their own though.
I tend to favor partially serrated blades...it gives you options but, I have an almost equal amount of plain edge. When I buy a knife I really like, which is most of them, I like to get both like the Tenacious (plain & partially serrated), Benchmade 710, Spyderco Enduras, Griptilians...well you get the idea.
It's like I always say...you need to have options...
Mostly, I prefer plain-edged blades. I do have a fully-serrated knife (Cold Steel Voyager in Clip)...but got it more as a novelty than for practical use. A lot of people voice dislike of combo blades. I generally felt the same until I bought a Cold Steel Recon 1Tanto in combo (originally bought this as a SD blade). Of all the combo blades that I've used (and I have several), this particular knife seems to work exceptionally well. For some time, I wondered "why?"; then it dawned on me. This is a larger folding knife (9 1/2" overall). The blade is 4" long with 1 3/4" of the rear portion serrated. You'd think that this knife would have two things going against it; the Tanto blade and the combo edge. However, those are the things that make this knife really useful. The Tanto point pierces well...obviously...but being a woodworker, I find that if I employ the tip of the blade like a chisel, I can cut all kinds of EDC materials very easily. For slicing across things, I just use the long flat portion of the blade. Then...when I need to cut rope, fabric or even cardboard, I use the serrated portion of the blade. I also have a Flash II Drop Point Combo that I use all the time...and while SOG's serrations seem to be inferior to those on my Recon 1, they do work fairly well. Again...the Flash II isn't a small knife (8" overall with just under 3 1/2" of blade...50/50 plain-serrated). That said, my Flash I...which goes with me almost daily...is just plain and I wouldn't have it any other way. So...this is a rather long-winded way of saying that if it is a larger folding knife (or fixed blade), a combo design can come in handy. Bear to sharpen? Yep...but this is really a matter of getting the right tools to sharpen your knife...and exercising a little patience during the task.