The prop balancer with the lowest friction would be the magnetic one from Top Flite or maybe its Great Planes? However, this balancer starts to be marginal on props bigger than the ones you are using. The magnets are not strong enough and the arbor will fall from between the magnets.

http://www2.towerhobbies.com/cgi-bin...&I=LXHY61&P=ML

I have three balancers. One magnetic, and two High Point balancers that at one time were sold by Robart.

http://bennettbuilt.com/page9.htm

The Dubro is also good.

http://www2.towerhobbies.com/cgi-bin...&I=LXD712&P=ML

The little jobs that you hold between your index finger and thumb are not very accurate but are better than nothing.

http://www2.towerhobbies.com/cgi-bin...?&I=LXK247&P=7

On the subject of props being in balance, MAS props seem to get the most complaints about the hole being off center. The Windsor prop balancer addresses this with a prop balancer arbor that allows you to reposition the hole.

http://www.masterairscrew.com/GoCart...68&RootID=1057

Props can be out of balance at the hub 90 degrees or somewhere in between that and the tips. When you start balancing a prop, you start with the tips and end with balancing the sides of the hub.

SPINNERS
Balancing spinners is as important as the propellers. Only the Dubro and some High Point balancers allow you to balance spinners