i use both the auto hudy and auto ofna. the ofna bogs down on big cuts and shuts off, the hudy powers through anything. I've never used a manual truer. fortunately my local track provides truers to the public to use so I've never had to buy one.
I use the Hudy truer (manual). It's a pain having to crank the wheel back and forth but it does the job. Make sure you get the Carbide blade. The regular one lasted me for one season (8 full sets between my brother and I per race day). The carbide doesn't snag or tear out the foam as easily. Just make sure you do at least 3 passes to get to the desired diameter or you'll tear the foam or delaminate it at the edge.