As it stands, the current balance is like this:
My thoughts for rectifying this are 1) to make Cavalry more expensive, and 2) I think Cavalry units should either have a penalty to fortification building speed, or simply not be able to build fortifications entirely. In fact, Infantry should probably be the fastest at building Fortifications (so slower for Siege and Ranged units and possibly not at all for Cavalry) and would give this unit class a realistic niche while preserving the relatively simple combat RPS mechanics in game. I get it, infantry has always been the meat shield compared to cavalry, but it was the core unit of most armies because it was cheaper, and you could use them to dig in. Civ 7 should reflect this better.
In addition, having only played with about half of the civilizations, I do think that most of the Unique Units are either good upgrades, or truly great ones. Except for ONE:
- Infantry is middle in cost.
- Cavalry has +5 CS compared to infantry of the same tier, ignores ZOC, as a higher move, and is a bit more expensive.
- Ranged units are both less expensive than infantry but have a ranged attack that is either better at killing units or districts respectively.
My thoughts for rectifying this are 1) to make Cavalry more expensive, and 2) I think Cavalry units should either have a penalty to fortification building speed, or simply not be able to build fortifications entirely. In fact, Infantry should probably be the fastest at building Fortifications (so slower for Siege and Ranged units and possibly not at all for Cavalry) and would give this unit class a realistic niche while preserving the relatively simple combat RPS mechanics in game. I get it, infantry has always been the meat shield compared to cavalry, but it was the core unit of most armies because it was cheaper, and you could use them to dig in. Civ 7 should reflect this better.
In addition, having only played with about half of the civilizations, I do think that most of the Unique Units are either good upgrades, or truly great ones. Except for ONE:
- Gold Bangles Infantry, the Songhai unit, which has very weird and situational benefits that are difficult to take advantage of. It should swap the trade route plundering bonus for getting extra gold from every pillage. It's easier to accomplish, and appropriately flavorful for the Songhai military. Also, the +5 CS on a resource tile is weird and difficult to use. If the devs really want to keep the bonus, I would suggest making it on/adjacent to a resource tile to allow for more flexibility and less strict placement for that +5 bonus. The bonus could be slightly nerfed to a +3 or +4 to compensate.