There are certain valid English words which just stick in the craw of your neck and you find yourself unable to utter them.
One, which I've run across a couple times recently, presents a dilemma: do you use the correct form of English, or the incorrect but more natural-sounding alternative.
Take the following sentence for example:
The world was not only more vast than they suspected, but was packed tight with congested buildings.
Is it just me, or does the word "vaster" just sound wrong?
If this is just my particular oddity, I'll swallow my pride and use it, but if, as I suspect, it's a general dissatisfaction with the legitimate word, then I'll stick to my guns and use the more natural-sounding illegitimate version.