I have not heard of a 'manual' brake controller any time recently. It sounds like it either has to be activated manually (press a switch every time you want to stop), or is 'binary' (brakes either full on or full off. In either case, I would avoid it like the plague...
You want a controller which is easy to install and set up, requires little or no maintenance, and provides the appropriate amount of braking in all conditions.
There are actually 'levels' of automatic brake controllers. Most will work ok, but some need to be 'set up' more than others. I like the Prodigy, which uses some kind of motion sensing or inertia sensing to determine how much braking to do. There is another one, I forget the name, which has a sensor on the brake pedal for how much it is pressed. That might be a bit more accurate, but a bit harder to install than the Prodigy.
John is right. The most user friendly brake controller on the market right now is the Prodigy. Everyone we've sold to says that they love it. We haven't had any complaints at all which is uncommon when it comes th brake controllers. It is more expesve than most (retails for around $145). Sometimes you can find it on sale.
Both are very effective, easy to use brake controllers that will make your trailering much more pleasant and safe. I would stay away from the other brands and models. There are a couple of others that cost a whole lot more but these two are acknowledged as two of the best on the market - both for ease of use and smoothness in braking.
The Prodigy can also be purchased with a plug in adapter specific to your truck so all you have to do is plug it in and go.