It seems the best saws available now are the steel-framed, European-style saws. Laguna comes to mind as the "gold standard", but there are good quality steel-framed saws being made in Asia, too. Grizzly and Rikon are examples of that. Apparently, it's a lot easier to weld a good steel plate frame and keep it in alignment than it is to cast an iron one that won't warp. I would not buy another cast-iron saw unless is was an older one that I could check for alignment, then recondition.

The problem with many (most?) cast saws is that the guide rod does not run perfectly parallel to the blade in both planes. As you raise and lower the guides, they move left-right or front-back and you have to re-adjust them every time you change cutting heights. This is very easy to check as long as the saw has a blade mounted in it. In some cases (typically with steel-framed saws), you can adjust or shim the guide mechanism if necessary to get everything perfectly aligned (I did this with my 10" Rikon). With cast saws, where the guide rod runs through the casting, they're either straight or they aren't and there's really nothing you can do about it. You can try to shim the frame at the joint, but that's a less than ideal solution. I have two cast frame saws with this issue and I haven't been able to get either one aligned.