Different sizes in test
XXS: 2 cc
XS: 5 cc
S: 10 cc
They are cheap, small and you can handle them very easily. They don't squirt much water, and often the diameter of the nozzle is too big for a good squirt. The best is the 10cc syringe if the nozzle diameter is small enough.
M: 20/30 cc
They are still very cheap (at least the 20cc ones), you can still handle them easily, and normally the nozzle has the right size for good squirting action.
L: 50/60 cc
Sure this is the most interesting size as water squirter because there are the most different models! You can choose out of four tips: Luer Slip, Luer Lock, Perfusor oder Catheter tip. They squirt a respectable amount of water, and you can get models for different sizes of water streams: Catheter tip 2/16 to 3/16 inch (3 to 4 mm), other tips about 1/16 inch (1,2 to 2 mm). Disadvantages: They are a bit more expensive, small hands can no more hold them as well, and with a small opening it is a bit hard to draw the liquid in.
XL: 100 cc
They are more expensive, normally available only with catheter tip and they have a very big nozzle of 2/16 to 3/16 inch (3 to 4 mm). Sometimes they also have a luer adapter that reduces the nozzle diameter to about 1/16 inch (1,2 to 2mm). Take it away for sucking the liquid in, and through the big nozzle and with the ring on the bottom you can do this very easily. For squirting you can choose to take a small nozzle diameter (with the luer tip put on) and a big one (without the tip). The ring on the bottom disturbs a bit in pressing well, and there is the danger you lose the tip.
XXL 140 cc
They are manufactured only by the factory "Monoject", and you can get them with Catheter tip, Luer tip and Luer Lock tip. I did not test them yet. I think it is hard and slow to fill them with the luer tips, but the water stream will last very long!
Here you can look at the syringes:
and here you can look at the complete series of 12cc, 35cc, 60cc and 140cc: