[aziaziazi]

What attribute should they have to make them more suited than helicopters? Silence ? Energy efficiency ? No landing pad ?

[xnx]

Lower noise, lower operating cost, lower purchase price, easier to pilot, more reliable (fewer parts), safer (redundancy), no emissions, faster time to air, configurable to requirements, etc.

[rpcope1]

Yes, I too want my space alien anti-gravity flying saucer. Those eggheads need to hurry it up.