Each unit has unique features, and the market is full of options right now. Freaky is correct, that the consumer must decide what is right for them. Whatever you are looking for is probably out in one form or another.

My suggestion would be to decide what is important to you. Ask your self the following questions.

1. Do I want sound?
2. Do I want a system that is 100 % Tamiya compatible. THis means weight classes, Battle damage, IR range, Reload delay and of course IR frequency,, and finally the abiltiy to plug in a Tamiya sensor.
3. Do I want to be able to program in different sounds.
4. Moving a system around between tanks is important to me.
5. DO I want momentum on my tank.
6. Do I want a repair feature in the tank battle simulation.
7. Do I want advance IR battling features, beyond the standard Tamiya battle damage

The questions above will help you break down the available systems by what they have to offer, and are important to you. Some can, and some can't deliver on the questions above, so there is way more to it then just preference, as all the systems are not equal on what they can do.