On paper, the Avenger is certainly the better carb. They are 4150s with secondary jets, electric choke and quick change secondary springs. The 3310s lack these features (although they can be retrofitted). I've used them before with good results on a couple of different applications.

There have been quality issues with the Avengers. Like many carburetor quality issues though, I'm sure many of these are due to installers knowing enough about tuning to be dangerous.

Holley also markets these as "bolt on and go carb". I think they are oversold in that perspective. Every carb can use a little tweaking to be optimized for a particular application. Holleys probably more so than competitors' carbs, but you can get a Holley way out of whack really quickly if you don't know what you're doing.