Need QUICK answer.
People...
There is a LOT of information already out there (on this board (and others)). Use the "SEARCH" button and have a look.
SmarTech's heli's are pretty much a direct copy of a Piccolo FP. The Dragonfly/Hummingbird (same thing) is an adaptation of the Piccolo. Parts availability is better for the Dragonfly/Hummingbird. At least in the US. I'm sure they all fly fairly similarly. You WILL need replacement parts. I would base my purchase that... But that's just me.
FWIW, I have a Dragonfly with lots of upgrades and it is a ton of fun. (And, frankly, I lucked into the right decission... bought it off of eBay on an impulse.)