The 1.1.7 Official Pre-Alpha, or

The 1.1.9 Work Version ?

Well, if you only need basic IDE features like source editor, project management and code completition, you can use 1.1.7 as well. On the other hand, the work versions often contains good improvements in the more advanced features like visual editing and standard libraries. For example 1.1.9 contains template engine that can create new projects very easy. The libraries are improved as well.
The risk is that the last work version can contains more bugs, but the true is that I even work on the last work version, developing Fresh and the problems are quite rare.
Of course, most detailed description of the differences you can find in "history.txt" file.

Regards.