The most important features of a good feeding syringe is the size (diameter and lenght) of the tip.
The problem with many syringes is that the tip is tiny and narrow. This is common with 2.5 and 5 ml syringes. With a 1 ml syringe, you can often saw off the tip with a serrated bread knife, and fit the whole diameter of the syringe into the bun’s mouth, but you can’t do that with the 2.5 and 5 ml syringes.
I prefer somewhat bigger syringes. They obviously have to be loaded from the back end, because you cant suck up CC through the tip.
I have 10 ml and 20 ml syringes for Critical Care. The 10 ml ones are feeding syringes for pets, which means the plunger doesn’t fit so tight in the syringe that a vacuum is created. This is very practical.
The 20 ml syringe I have has a detachable flexible plastic tip, which is practical because it reaches well into the bun’s mouth. The downside with that syringe is that a rather powerful vacuum is created inside, making the plunger very stiff after a few uses.
Stiff syringes can be lubricated with a few drops of simethicone baby gas drops.