@aeva Hmmm, for me the main factors I can think of are, in order of importance:
my current financial availabilityhow much use I find for the softwarehow much potential I see in the software for the futurethe absence of dark patternsthe availability of the source codehow transparent the developer is with the payments they receivethe platform they collect payments on(Example: I really dislike paying via Patreon due to poor previous experiences, even more so if the creator does not display the current number of patrons and the amount of money received per-month, but I’d still be willing to pay there if the software is very useful.)