On the whole, something like QJ is not quite as good as xxx, opposite xxxxx, even though there are some situations where it is better. More to the point, KQ is better than xxx because its sheer strength compensates for its lack of length. And KJ is an intermediate case because it is like a KQ if the opposing A is "onside" a finesse, and like a QJ if it is offside. A QJ may be regarded by some as an "adequate" substitute for xxx, but only in a "pinch." And it does have the potential to cause some partnership misunderstanding.
The disadvantage of the two high honors is that it gives a sixth card to the opponents, and possible distributions of 3-3, 4-2, 5-1, and even 6-0. An opposing 3-3 is no worse for you than a 3-2, but the 3-3 appears only 36% of the time compared to almost 68% for the 3-2 (you have eight small cards, the opponents have five). A 4-2 distribution is no worse than a 4-1, but your opponents get this 48% of the time, versus only 28%. So we have to look at the 20% "overage" for 4-2.
If your xxxxx in hand is actually T9xxx, then you're better off with the QJ because of the resulting sequence. They will fall to the AK, but your T9 will pick up the remaining opposing low cards and your fifth card will give you a third "long" trick. (T8 or 98 will also work of the opposing singleton is the missing intermediate card.) If my low cards are 65432, I'd rather have 987 opposite than QJ, because of the larger number of times that the opponents' 4-2 will give them four tricks in the suit than 4-1. Similar arguments hold for 5-1 versus 5-0.
My answer is the QJ. Declarer is likely to have Kxxxx, Axxxx, or even Txxxx, in which case, the QJ will be more valuable as "filler" than the extra low trump would be. It would even be helpful opposite AKxxx or AKTxxx.
With KQ opposite xxxxx, you're actually better off than with xxx. The KQ is a sure trick, and you will take a two "long tricks" (total of three) if your opponents have 3-3. If they have 4-2 with six cards you will take only two tricks, but you're no worse off than with and opposing 3-2 and no honors opposite.