The combo drives have one great advantage....they are considerably less expensive than the blu ray burners. Other than that, I believe its a toss-up on dvd burning. All of the major brands do an adequate job of burning dvds these days, especially if you stick to good quality media.
There are a few dvd burners that stand out, like the 24x Samsung, or the last couple of generations of Optiarc drives, but those aren't combo drives.
And you have to take into consideration the experiences/prejudices of the people you are asking about these drives. I personally have never liked Lite-on drives. I certainly wouldn't buy one of their blu ray burners, since they got into that segment of the market very late and are still catching up to Pioneer and LG. The Lite-on blu ray rom drives were good though and capable of performing quality scans on blu ray disks, so a Lite-on combo drive might be perfectly fine.
But there are other problems for the other brands. LG is notorious for slow/nonexistent firmware updates for their drives. Optiarc doesn't make a combo drive or blu ray burner. Pioneer has started using QSI for their latest dvd drives and the jury is still out on those drives. Plextor hasn't made their own drives in years, but still charge an outrageous price for the name....don't buy a modern Plextor.
The combo drives and blu ray burners seem to use older tech in their dvd burning side...16x max speed for example on single layer dvds. This level of dvd burning should have very mature firmware available already. In other words, they aren't pushing the envelope on dvd burning with these drives, and all should be fairly similar in abilities with dvds.