I think my favorite is the 1994-2007 period, not all series are my favorite, but this is the generation where I accessed Gundam first, and became my measuring stick for future series.
You have to owe G-Gundam in saving the franchise, and Wing for introducing Gundam in a general audience to the West (much of the consternation of UC fans, though 08th MS was made to compensate for it and it can stand on its own). After 00 it became, a bit less interesting though they still have charm.
I disagree with the above poster saying they should stick with UC and Build series; I do agree that the AU series be explored further.
Besides, there is the Gundam Burai manga, why not turn it to anime?