I can think of three types:
One and Only Gig
A unique gig with no or only few similar gig. Think of “christmas hat design”. Probably zero buyer, though.
A gig on heavily saturated market (ie. thousands other similar gigs) offering much more features for much less price.
A gig with small but noticeable differentiation. Unreal example: “design business card for graphic designers”.
Which one of them you think will have more sales?
Or, maybe you got other types?
With all respect, please don’t give OOT answers like: “anything is good, as long as blabla…” This is a technical question, not motivational consultation.