MapTool Version 1.2
This is the latest "officially stable" version of MapTool. It has a number of highly useful features, but by comparison to the latest 1.3 development builds is relatively feature-light. If all you want is the guaranteed most problem-free MapTool experience, you may at least want to start here.
Of late, the majority of 1.3 builds are really just as stable, and are massively improved. A good example is the integration of a built-in intiative tracker that in conjunction with tracking of token properties makes the less-convenient-by-comparison IntiativeTool redundant for most users. Some development builds can have stability issues, however, so it's a good idea to ask around on the forum to find out what the most recent stable build is at the moment.
And be aware that the campaign files saved by version 1.2 will not be readable by version 1.3.b19 or later (there was a drastic change in how data was saved that makes the files incompatible).