Any of the three common Antaresia species (stimsoni, maculosa or childreni) would be perfect for you. They're a very convenient size, they'll fit comfortably into even a very small apartment, they're easy to care for, and come in a range of prices to suit any budget.
You'll get people touting some as better than others, usually because they love the one or two of whatever species they happen to have, but I've worked with literally thousands of them and can say they're all really good and the main difference is the colour and pattern. Blonde Spotteds tend to be the largest, then other Spotteds, then Children's and Stimson's are slightly smaller, but there's not much difference at all in size. If you get one which is an established feeder and know what you're doing with husbandry you should have no problems with any of these and they're fantastic snakes with the full personality of a python packed into a small package.