It's now getting to the point that PrestaShop has a lot more features than the free version of Magento, so I would if you want to spend thousands a year to get the best, get Magento. If you want a great community which releases all sorts of modules and themes for free (along with a bunch of great paid ones), PrestaShop is the way to go.
One big thing that I want to do is give people vouchers/coupons, so if I meet them or sell them something, they can use the coupon on another purchase. It's built into PrestaShop, but with Magento you need to give them a lot of money in order to use that feature. Albeit you get a lot of features for a lot of money, but for a lot of small businesses, it is a lot cheaper to use PrestaShop and pay professionals to work on it and pay for some modules than shell out a lot of money every single year to Magento.
Oh yeah, when you pay for Magento, you are only getting a one-year license. I was really into Magento until I found this out, now I don't give a damn about the company or it's faux open-source project that they have swept underneath the carpet.