I think it depends on following
a) Cost analysis. This is the major factor. Older techonologies are cheaper, but then die size increases, and so does package size/cost as well, and yield and dies per wafer decreases.
b) speed of process
Depending on what speed you want to run at, some techonogies might not be a option at all. You don't not need 65nm if your logic is going to run just at 100Mhz or so, but if you are going to multighz, then 130nm kind of technologies are out of question.
c) power consumption
If you are too much concerned about power, you need to decrease the voltage of operation, hence go for smaller techonologies like 40nm/65nm.
d) voltage requirements - In some cases like power electronics, you have to work with very high voltages, so again small technologies might not be a option at all.