Oscar Liang says you can increase reception by just putting circular antenna on your goggles. You get more gain even though you lose about 30% of the signal from the linear antenna on the quad.
If you want more - then you will need to put circular antenna on the quad as you've suggested, also.
Again, I'd just go with omni's, but if you are still having problems with reception you can go with directional. With directional you will need to keep facing your quad. In my yard I don't always fly in front of me so I feel omni's are better.