You will find many of the most easily recognisable logos you will find are very simple. Many large companies just use a particular font style with no logo (Coca-cola, Exxon, kleenex, Google, McDonalds, IBM, yahoo), while others use a simple circle and text (Mercedes, BMW, Texaco)
Look around at many of the popular sites on the web. Keep it simple (MS Windows, Adobe, Shell, BP), so people remember it.
Out of all my examples, for a pure logo, id say Style 1 (Simple circle and text) is my favourite, as I can remember it easily and draw it out of my head. Plus its like a new improved evolution from the old design..
Though thats simply my own biased opinion.
