What other title for "Receptionist" is most impressive to a future employer?

This depend on the role.
I don't prefer receptionist title as it is very narrow scope.
I prefer to use other titles like secretary or administrative assistant as this give better chance for enrich job and career development.

Public Relations Officer

Front Desk Agent or Attendant.

Customer Service

desk  clerck

Receptionist .......
is the best title

Front Office Execuitve.

Front Office Representative

It depends whether the "Receptionist" has got some more duties to be performed or simply looking for future impressive title.
They are many, 1.
Administrative Assistant(if some change in job): Taking care of freshers position, handling phone calls, e-mailing, arranging conference rooms, tracking data etc; 2.
Front Desk Officer: A receptionist also manages daily activities of the office.
3.
Company Support Representative: It also represents on behalf of the company, you could also call C.S.R.

If possible minimise or do not use the Receptionist title as it is quite limiting in its portrayal of office workers.
To most businesses and employers receptionists implies that yes a person knows how to answer the phone and greet people but that's it.
We know that receptionists work very hard but that job title does not do applicants much service.
Other options: Administrative Assistant Office Assistant Secretary - if you have other skills to add.
indicate to the employer that you have various skills and willing to learn new skills.

Receptionist is best but alternative you can use front desk officer, front desk agent etc.