Be aware that 'preferential' can imply unfair advantages or bias. The boss's son seems to get preferential opportunities at work.
Pro Tip 2/3
Neutral Vs. Negative
'Preferential' can be neutral, but often has a negative slant in informal contexts. Despite her qualifications, Jane felt she lost out due to preferential hiring.
Pro Tip 3/3
Not Always Overt
Preferential treatment can be subtle and not easily noticed. He quietly received preferential seating at the event.