Personally I'd say there is no difference; I've stuck out on syringes in the uk for ages just because I found them lightweight and convenient; but recently moved to pre-filled pens. The cost to the NHS for prefilled pens vs syringes is pretty negligible.
Syringes were fine for me, pens might be less embarrassing to use in public maybe?
are we talking the same thing, I am thinking of the pens I used to use that you would dial the dosage in and then push the plunger. In Canada, those pen fills costed about 70 vs 36 for the vials, but they also had 15mL of insulin vs 10mL. So about 1/3 more with the syringes and needles being about the same price.
The problem isn't their choice of insulin delivery, it is that there are no price controls and an incentive to increase prices without any significant loss in sales. This is an area that government need to be all over.
Syringes were fine for me, pens might be less embarrassing to use in public maybe?