I always have and probably always will advise a corn, or(my favorite close cousin) gray ratsnake, as the best first time pets. Sure, there are plenty of great candidates but I think they are the best options for someone that likely wants to handle a fair bit and will almost certainly make some mistakes along the way. Even wild examples, 9/10 of the time you can pick them up and only get bit a couples times(sometimes not at all) before they're chill. A couple years ago I found a rather skinny looking gray rat in the yard and walked him over to one of my known tree frog haunts and held him up so he could pick off a few easy meals while wrapped around my fingers. He didn't bite me at all as far as I remember but the main point is, he didn't get turned off food by the encounter. A year or two before that some heavy rains drove a hatchling gray rat to take refuge in my home. He was a fresh baby, that had just got the poop scared out of him by some crazy dogs, but took a couple pinky ASF like an old pro the same night. I released him the following day after the rains stopped.

King snakes fall into a similar category of basically being bulletproof but they also tend to be more food oriented. You could end up with a gnawer if you don't feed enough or work with the snake often enough - sometimes even when you do.

Garter snakes are also hardy but not nearly so much as ratsnakes and kingsnakes. They can also be very musky and bitey, though this varies largely from species to species, and they can be worked out of it most of the time. They are tiny though and flighty as babies which can be just as intimidating to a new keeper as something larger and aggressive. I often affectionately call my infernalis little bitey poopcopters. They are always hungry and my fingers look close enough to pinkies that they want a taste. They also don't just musk, they musk while twirling their tails like little propellers to send crap flying all over the place. I'll probably get around to working with them when they get a bit bigger probably but for now I find both attributes, more or less, kind of endearing - doubt a new keeper would feel the same.

Ball pythons are great but not as forgiving of keeper error as the above choices. Even when you do get all of your parameters "right" you might still need to tweak around with things to get them to really thrive for you. While all of the above will take to f/t without a hitch, ball pythons can take a fair bit more work and when they inevitably do go off feed they can be stubborn getting back on to f/t whereas a live rodent might get their attention sooner. Also, you have to remember that a fasting royal isn't uncommon or unnatural. If you feed f/t though and this is your only snake, be prepared to throw out a fair number of rodents throughout the year.