I would preferably like to see Angola or the DRC myself. (but preferably Angola as it has a coastline) And I'll tell you why...
Firstly, the terrain is mostly very rural, which would not only avoid large, time consuming cities to be created, but would also aid in game performance. As well as providing an excellent landscape for ground wars with a good mixture of bush, open savanna and small rural towns. Thirdly, although the previous mentioned alternatives have all had their fair share of conflicts, Central African wars offer a far more realistic solution due to the fact that DCS can not handle the amount of units that would realistically take place for instance, in a European conflict. African style battles take place on a far smaller scale, and lend themselves to the performance capabilities of DCS far more... And due to the fact that the region is also very unstable, it offers great possibilities for missions and campaigns. Lastly there are already a lot of modules available for aircraft that have taken part in Central African wars such as the Mig 15, Mig 21, Mi-8, Uh-1, Su-25, F-86, P-51 and Mirage, with more on the way. Not to mention that a large amount of existing AI Air and ground units have also served in the African theater.
Another terrain I would love to see that hasn't been mentioned is the Falklands. I think it would be a perfect fit for Razbam's up and coming Harrier Mod (be it the later models) and would also offer performance advantages due to it's small size in comparison to other maps as well as realistic amphibious and naval scenarios. Plus it would hopefully lead to the continuation of the A-4 Skyhawk and the development of an Invincible class carrier mod.