I would basically not recommend the el-cheap ones with a rubber cap. The friction on them is horrible. The Wacom bamboo one is decent, as is the Alupen, and the Ozaki, but that's expensive.
Unfortunately the iPad isn't super accurate for handwriting, it helps to use apps like Notetaker plus which shrink your handwriting down.
I am unsure of the brand but I saw this pen-type stylus at an iStore for R300. It has a tiny ball on the end that's covered with a transparent pad as to give it a larger footprint. I used it a bit on my Archos G9 and it worked WAY better than anything else I've tested.