To me, the preferred choice probably depends on how you were first introduced to enemas…. sort of like imprinting. It is well known that early childhood experiences can have a lifelong influence on your likes and behavior.
For example, if your mom made you eat every carrot on your plate, you may now detest them.
The same applies to enema syringe preferences, IMO.
So, if your first memory is of standing between your mom's knees, bent at the waist, bare, bottom and hearing her slurp up soapy water from a nearby bowl, then feeling your cheeks being spread, followed by a surge of warm water into your most intimate recesses, soon to be followed by additional bulbsfull, and then an urgent desire to poo, in later life you may crave to relive that experience.
In the same way, if your first introduction to enemas was being told to go to your bedroom, undress, lay on the bed, then seeing your mom walk in carrying a filled enema bag and experience the feelings that only a bag of warm water can produce, that may well be what you desire.
If your first introduction as in a hospital or from a professional nurse who used an irrigating can to, that could well be what you like to relive.
Obviously, any of the three, bulb, bag, or can can fill a person's bowel with enema solution. And, no matter which you choose, the effects will be identical. The only variables are solution type, quantity given, and retention time. If the results are compared, nobody can determine that poo was caused by a bulb, bag, or can,