You have things you need to look at like are you looking for more of a spot, or flood of light. Some are better at one than the other. M&R and Rigid makes good units. I think KC is making LED units now, but not sure if they are light bars.
Good LED light bars are expensive, some can take a .22 bullet without any consequences, and thats what I'd want if it was going on the bumper area.
And yes, they all aim the light differently, some spread the light, others focus it like a beam in one spot, etc. So make sure you know what you're buying.
Sometimes you can get lucky with cheap stuff though too, sometimes ... I bought some 10 watt LED lights, and they were 20$ each or something, and they're going on 3 years I think. They had a solid aluminum housing, and glass lens. I'm cheap though, and not planning on spending hundreds of dollars on a light.
The Rigid lights are good quality and super bright. The only thing you are sacrificing by mounting them behind the grille is the height. The higher they are the better they illuminate the ground. So the higher you mount a light on a truck the better you will see things.