I have owned several tablet pcs, and now have a definite bias which is based on my experience with several.... I strongly prefer the tablet pc devices which use a touch pen interface as opposed to an electronic pen one. What this means is that you can use your device with the pen which came with the tablet; any other stylus object; your fingernail; or any other object which will not damage the screen. The electronic pen tablets are designed to be used only with the pen which came with the system, since it is based on communication between the pen and the screen surface.
For my work style, I have found that my devices which are touch based are far easier to use. I also end-up using the pen much more than the keyboard.
When the tablet pc form factor was first released, the majority of devices utilized the electronic pen. I believe that might be one reason the sales were so low and the public didn't adopt it like Microsoft had hoped.
I am sure there are people who have the exact opposite opinion to what I am sharing. I suggest that you not spend much money on a tablet pc until you have an opportunity to try both types of pen input and decide which works best for you.