While the Plantagenet Golden Bow is the superior option for your Archer General. It is not available to the majority of players. In the case that you don't have it, the Ares Bow is the next strongest option. I see many new players make the mistake of thinking the Achaemenidae is better because it requires a higher Forge level. But the Ares Bow has better marching buffs.
Again Plantagenet takes the top spot, unfortunately the only other option that helps your Archers at all is the Courageous Ares Armor.
Freedom Boots reign supreme due to them having a huge Marching Archer Attack buff. No other boots have an Archer Attack buff, but you can pick up a Archer HP buff from either Fearless Ares or Achaemenidae if you don't have the Freedom Boots Scroll.
NEW: Abbas Helmet is the logical and best choice for your Archer general as it provides the highest Archer Attack buff of any Helmet
The Han Dynasty Helmet is far better than the Fearless Ares due to the higher Archer Attack, as well as an all troops HP buff as well. Don't get discouraged if you don't have the scroll through. The Ares Helm is still a very strong piece of gear.
Plantagenet wins out again by a slim margin! But fear not! There are other Civilization Gear options that are perfectly viable. The Freedom Pants give a strong Defense buff as well as they could unlock a strong set bonus if you also have the Freedom Boots. The Furinkazan Pants also give a defense buff along with the Archer Attack buff but won't get you a set bonus. If you don't have access to any of these pieces, the Courageous Achaemenidae Pants will also sneak you in some Archer Attack buffs in the meantime.
The Plantagenet Ring is the clear choice for your Archer General. A strong Attack buff as well as a March Capacity buff go a long way towards making your Archer march as strong as possible. In the meantime, the Fearless Achaemenidae Ring will work wonders until you can replace it with the Plantagenet. At that time, it becomes a hand me down to a sub gen!