If you're taking only quarters, I'd go with a Sensortron or Slugbuster I. The SB II jams more easily, has a tendency to fall apart and will steal dollar
coins from your customers.
If you plan on taking multiple
coins and/or
tokens, I'd recommend IDX or Slugbuster III.
Dixmor is the best dixplay timer hands down, rugged and reliable and inexpensive to repair if they have a problem.