We used to use Vista, but then had a problem where it took them over 90 minutes to come get us at the airport on our return because "they were short staffed and didn't have a driver," and we haven't used them since.
We use AviStar now, gated, secured lot and they are definitely a lot faster and more efficient than Vista. They give a AAA discount.
I would never leave my car in long term parking at Newark. The Star Ledger did a story on the car thefts and break-ins in the long term lots a few years ago, it was both eye opening and appalling!
Anne