Alright, time to dig into this.
Ben does have a good variety of aliens, each having a rough 2x AP advantage, but none of them really pose much of a threat that's out of the ordinary to Spider-Man. Ghostfreak is probably the biggest problem, but Ben won't use him. Why? Because it's in Central Park in the middle of the day, and Ghostfreak is weak to light without the first layer of its skin. Still, even if he isn't harmed, his invisibility isn't going to do anything when Spidey can sense him just as easily.
Spider-Man has prep, which will undoubtedly give him access to any suit he thinks is necessary. The Mark IV is a safe bet due to the versatility the suit has over his stealth suits and it being his most modern suit compared to the other Mark armors. His Z Metal Webbing counters any energy Ben's aliens can throw at him by absorbing it and redirecting it back at him, while his other forms of webbing (acidic, concrete, etc.) can be used for more of a distraction if nothing else.
Not only that, but he has years of experience and has greater skill than Ben does and fought a far wider variety of people than what Ben has access to here. His standard webbing is also good for defense as much as it is trying to entangle Ben, acting as shields that can hold up against any projectiles or damage. He also has crazy mobility with his webbing, and even without it he can really move like a slimy spider. That's not even mentioning his Spider Sense, which gives him a very distinct advantage to make up for the AP gap between him and Ben's aliens.
TL;DR: Spider-Man for superior experience, skill, versatility, webbing, mobility, and Spider Sense.
