In my professional opinion, as someone with professional training as a graphic designer, number one is your best bet. It is the cleanest and reads the best. It is important for logos to be clean and simple or else they do not read well. They must look good when they are only 1/4 of an inch in size, or when blown up 20' tall on a billboard, and they must look good in black and white and in color. Number one achieves this the best.
Number 3 would be my second pick, however the text will become hard to read if the logo is done on a small scale. Design number one has the advantage in that the text and the actual graphic symbol are two separate parts, which IMO is ideally what you want. When the text itself is part of the logo it can be harder to read, both as a word or words, and as a symbol.
Number 2 and 4 simply do not read well when small. The lines on 2 are too thin and lose definition. Same with the text on 4 - if you had that on a business card it would be hard to read the text. They are both nice designs, but IMO not very good logos.
Remember: simple, clean, easy to read, easy to identify, looks good at any size in any color scheme. That is what you want with a logo.
