Microwave Stub Design(Choice between Series & Shunt and Open & Short)
Assuming you are designing a microstrip stub (not coax cable), the exact electrical length is quite tricky to figure out beforehand. An open stub can be manually trimmed for adjustment, whereas a short stub can't.

More in general, both open and short stubs can be used and will have different lengths in each case. The geometry of your design may better accommodate for one rather than the other. Not always you will opt for the shortest: sometimes the shortest stub will be too short for it to act as a proper microstrip line (i.e. comparable to the strip width).