I'll take Zeros over Aliens. One of my climbing partners worked really hard keeping a guy alive when his Alien separeted at the braze when he weighted it (not fell) and hit his head on a ledge (he had a helmet on but what possibly saved his life is that he bled pretty badly preventing excessive pressure to the brain, so I REALLY don't understand why people STILL like or love their Aliens)- go figure.
I'm sorry. That sounds horrible. I can't speak for anyone else, but I trust my Aliens simply as much as I've tested them (which is to around 4kN).
But the C3's absolutely rule. There is a .13a crack that I've tried to get the second ascent and I'll try again shortly that requires only black aliens (or purple C3's) for 30-40ft(before going to offwidth- go figure). The 4 lobes of the Aliens are a bitch to get into it, and often ends up being a really manky placement once I do get it in, but the purple C3 goes in so easily that it feels like I'm cheating, but has held pretty good wingers (and this is pretty soft sandstone).
Glad you like them!
And certainly, as long as different gear is, well, different, there will always be placements that are better for one or another style.