After having used the 3PK for some time, I must say this is the best radio for the money.

I like the fact that it feels balanced in your hands, this is important in a long main.
It's large screen faces you (mostly) which is very handy if you need to sneak a peek while your pitman is refuelling in the battle during a race.
It has built in failsafe, both for Rx low-voltage and radio interference. No need to get a seperate unit to plonk on your car.
It's menus are logical and has everything you'll ever need for car racing.
It's timer is easy to set if you need to keep an "ear" on your fuel.

I like the Sanwa M8 also but its slightly heavier, no failsafe and I find the timer awkward. Its also more expensive than the 3PK feature for feature.

I have not tested or tried the Ko-Helios. The ergonomics looks comfortable but still no built in failsafe.

All in all, I would consider these 3 radios if you prefer to use the wheel type. 3PK first, Sanwa M8 and then the Helios.