I would say it's down to which you like best, they are so similar that your not going to see a lot of difference between them.

The EF Yak now comes with a superbly made ply motor mount for a outrunner type motor, I'm not sure if the Ultra Rc range does though, I guess someone else could shed some light on this????

I would say an outrunner is the right thing for this type of model, it's got more torque than most geared drive and it's smoother than most geared drives.

But if your not going with an outrunner then that is irrelevant, again it's not going to be that different with a gear drive (ie. it's still going to be AWESOME!)

Here's my setup on the EF Yak:

Motor: Extreme Flight Torque 22T/930
Battery: Flight power Extreme 3s1p 1050
ESC: Castle creations Phoenix-25
Servos: HS-55 x4
Rx: Blue Arrow R3P5
Prop: 10x4.8

And thats never missed a beat[8D]!

So I would say that they are all going to be similar, pick out the one that stands out for you.

I hope this helps a bit.

Greg.