The Air Train is a big reason why I hate EWR. You've got an elevator ride from bag claim to the upper level, then a second ride up to the Air Train. Once at the rental car station, there's a third ride down to ground level. On the return to the airport, with some rental car companies (Hertz for sure, not sure about Budget), car return is on the second level of the garage, meaning yet another elevator ride.

If you're traveling alone, options are limited, but if you have a companion and a ton of bags, the easiest thing would be to take all the bags from bag claim out to curbside together, then companion waits with the bags while you schlep out to get the car. Then then drive back to the terminal to pick up companion and bags.