Hitting more often is always the best.
Take your example. Fast weapon (lower damage) versus Slow weapon (bigger damage).
Ok, if you swing over a time period of 30 seconds.
Fast weapon (1.25) swings 24 times.
Slow weapon (4s) swings 7.5 times (Lets make it 8)
Now out of those swings, how many times did you hit? Lets say it's 50%.
Fast weapon (1.25s) swings 24 times, hits 12 times.
Slow weapon (4s) swings 8 times, hits 4 times.
So basically, you would need to do 3x the damage with the slow weapon to do the same damage the fast weapon does. Remember these numbers are only for an example. But the basics hold true.
The best is to find a comfortable balance between damage and speed. And consider what it is you'll be using the weapon for.
Doom - for example - you can get away with a heavy thumper because your not having to deal with anything targetting you. Of course a lighter thumper that swings faster will give you more overall damage.
And probably most important of all is the ability to hit.
120 Archery + MAX HCI really helps.