When using a gear drive:
There is a slight advantage to a ratio that is not x.000:1 Best will have x.xxx:1 where no (x) number is 0. This ensures that each tooth must hit many other teeth before hitting the same one again so that any small defect will take longer to progress into a broken tooth.
Not a huge consideration for us.
Direct drive is better, mechanically... when you can do it.
Geared is better for efficiency if the gears are of high quality. A low kV motor wastes more energy than a high kV motor because electric motors simply work better at higher rpm. The efficiency differences for our purposes is again very small because small motors tend to be a bit inefficient anyway.
So in the end: Pick the setup that makes the prop turn the rpm you need. It will be fine.