[chrisguyw]

What motors do you most often use ???.........this will determine the ohm rating of the controller.

For typical Scaley motors a 35ohm will likely be just fine,...that said, as your track will be quite tight and twisty (on a 4 x 8), a slightly higher ohm value may be beneficial.

For most club racing using moderately quick motors (20/25K) a 25 ohm will be a better choice.

You may want to seriously consider an electronic controller (with a sensitivity pot), although initially more expensive, the sensitivity control will allow you to dial in a wide range of motors. (and tracks)........if you race with a range of motors (slow to fast), you will end up buying a few fixed ohm controllers, and these will not offer the fine tuning of an electronic. There is no need to buy one with all the bells/whistles,.....a good quality electronic controller with sensitivity adjustments can be had for $100 (ish)..........you will be happy you took the plunge !!

A good power supply and good controllers are the two best upgrades you will ever make 

Cheers
Chris Walker