I'm about to download the source code for glade from http://glade.gnome.org/sources.html it has two options stable tarballs for Glade 3.8 for GTK+2 stable tarballs for Glade 3.14 for GTK+3 which one should I pick if I'm running ubuntu version 12.1
It depends upon whether you want to develop an application with GTK+ 2 or GTK+ 3. All newer applications should be developed with GTK+ 3 because GTK+ 2 has reached its end of life. Nevertheless, there may be legitimate reasons for developing an application with GTK+ 2, such as backward compatibility with older distributions.
I'm not sure if you are aware of the fact, that both versions of Glade that you've mentioned above are already packaged for Ubuntu 12.10. You can install Glade 3.14 using the terminal with the command
and Glade 3.8 with the command
There is actually no need to manually download and compile Glade, unless you want to develop Glade itself.