Would prey be better off or worse without predators?

If there were no predators, the "prey" would increase in size so much that they would eventually starve to death.. There would be TOO MANY of them for the available food supply

Worse, they eat themselves out of house and home. Witness the rabbits in Australia, or rats on an island with no predators.

worse. they would become severly overpopulated and there wouldn't be enough food to go around.

Worse

They would be worse off in the long run. Prey do two things to a population. First, they keep its numbers in check. Secondly, they often take as prey young, old, injured and sick animals leaving the healthier ones. We have seen in many cases where natural predators are locally extinct and the prey population has grown too large. That population suffers the problems of being too large such as stress, high parasite load, disease, food shortage, etc. Prey species when they get too large also damage the environment because their large numbers consume too much vegetation. Simply the ecosystem's balance is lost.

Prey animal populations would explode to unbelievable proportions.

worse in the long run, because they will evolve to lose their fear. Later, when new predators appear, they are literally sitting ducks, easy prey because they have no fear and no way to defend themselves. For example birds that evolved on islands often lose their fear and their ability to fly, if there are no predators on the ground. When predators such as humans arrive later, these birds (e.g. the dodo and the moa) can be easily hunted to extinction.

For the individual, better, for the species, worse.

That depends.

Humans: we're better off without leopards eating us.

Deer: better with predators. In a scenario without predators, the deer eat everything and then starve.