I'll be the first to chime in- These comparisons usually break down into 4 categories-
Features can be easily compared on the company website. My guess is that you have already decided which machine offers the most in lathe and milling.
Quality is more difficult to determine on your own without actually buying one of each brand and finding out the hard way. I have owned 2 Shoptask/Shopmaster machines and found the quality to be fine for the price point. I don't know about Smithy, but I would be wary of any sales pitch that claims some superior degree of quality from a Chinese factory, especially if the price is similar to the competition.
Service is a major issue for most people, and reading these forums, you will see that both companies receive reasonably good reviews, with each having the occasional hate mail. Looking at the overall picture, Shoptask has been around for 30 years- Smithy about 25, so you can take some comfort in knowing that both are pretty solid.
Price is another black and white comparison you have probably already done. Shopmaster offers a machine with 4 axis CNC, VFD drives and 3 axis ball screws for 4995.00- The Smithy, if outfitted the same way, I think will be substantially higher.