My main hobby is cycling, I'm just getting into this quadcoper world. Cyclists often quote a 'rule' that the minimum number of bikes you must own is n+1 where:-

n =  the number of bikes you already have
1 = the next bike you are planning on buying.

Now I suspect this sport is similar, so here's my n+1

n - DJI Phantom 2 Vison +. Which actually belongs to work, so
1 - iFly 4s - I'm thinking of buying 2nd hand as I can't afford/justify a Phantom of my own.

A short list to start with, I'm sure you can do better. (I'll share my bikes if you're interested, that's a bit more complete. )

Not sure this qualifies but it might. I have a Phantom 2 Vision+ for my professional side of things. But I enjoy flying the JXD388 much more. It is a cheap($35) toy quadcopter for flying indoors, but this darn thing is so fun to fly I can't get enough of it. Fully manual controls and it even does flips in all four directions. Like I said, not sure if this is what you mean, but I thought I'd share.   And I would have to say my N+1 would be the professional series multi-copter from DJI that will carry one of my DSLRs, like the Spreading Wings Series. Can't afford them, but would love to get there eventually.

Tony@CVP Posted at 2014-9-25 11:27
Not sure this qualifies but it might. I have a Phantom 2 Vision+ for my professional side of things. ...

That would be so awesome to afford a way to get my canon 5DIII in the air. Need some better paying jobs LOL