You don't need GDRs and nukes at all though, Bombers and fast cavalry type units are extremely efficient and come online a lot earlier. Usually I get myself 2 or 3 bombers and a token force of cavalry type units, and I can easily take a city every 1-2 turns from that point on. It's so ridiculously easy compared to how it is before I get bomber (or balloon) tech, it's almost like night and day. That being said, bombers should also be nerfed if they ever reduce the wall strength, as clearly the problem lies equally in how fast bombers can flatten any city defenses once you get them. I disagree that nerf would hamper my enjoyment. I already use the "stupidwalls" mod that reduces wall health by 50%, and it somewhat rekindled my interest in the game after I burned out from the repetitiveness before christmas. If the walls were nerfed even further, that would be a joyful day for me personally.