Which would you choose for a factory or mild built 454 and why?

I'd say Holley all the way.  Edelbrock carbs are really only good for mild street use, not much more than that.
In my opinion, the best option is to get a custom carb built to your engine specs. Most of the custom carb builders use Holley main bodies anyhow. I have a Pro Systems carb on my SBF. Didn't cost much more than a Holley HP.
Once I got it dialed in, the thing works amazing….  

Which would you choose for a factory or mild built 454 and why?

Told ya i got that Holley ....

Or I'll sell ya an Edelbrock in a couple weeks