1) logo should be design in 2-3 colors and you have to check it with black and white print also. so in case if you have to print it in b-w in future, it should be looks good.
START in black and white. Think for every color you have, you add a plate, or a Pantone matching charge. I'm sure the OP knows what Pantones are, right?
2) icon must represent your company nature and its work. also it is going to become your company icon and people going to recognized your company only seeing its icon. so it should be clear and conceptual.
Yeah, good thing they're not selling underwear. Is your personal logo a person at a computer wearing a lightbulb t-shirt?
I definitely prefer the fifth one. But to be true, I understood what the initials are only after reading your message. Though, when I saw the second one, I've thought about RH. I think you need to work...