Snap-on is nice if you work in a shop and they come to you for sales and warranty stuff, and they make it a very easy process. Plus, with snap-on, you might pay more up front, but it should last you for the rest of your career, if not your life. So yeah they're expensive, but you only need one.
If you don't have a truck that visits the shop, then I'd buy the tool from the company that actually makes it, if at all possible.