Lets talk bows....
The general consensus from past threads was the Duskhill is the "best" bow, and if you could ONLY use one bow, I'd agree.
Being you can switch out equipment, I'd argue that the Ruby Bow is the best in all but for siege assault (or in the rare case you want to weaken a unit to capture it).
The Ruby is slower, its not nearly as accurate, but it will one hit kill all but the VERY toughest units. Duskhill will routinely take two on high tear armored units.
You won't max distance sniper with the ruby, but thats not where most of your kills come from. On the other hand you will tear through knights of the lion and the like in a way that will feel like cheating, and in siege defense where you get them coming up a ladder or a tower, its just insane. My record was 273 kills vrs that Immortal army spawn trying to sack Ethos. Being able to one shot most of the units (and large stacks of arrows, plus a few... er "accidents" by my bow men) made that a lot easier than trying for only head shots or double shooting them.
Edit: I want to add, whoever did the model for the Duskhill did a fantastic job, its gorgeous. It just looks and feels right, and I'll find myself sometimes just using it for the esthetics of it.