I don't think there's one best tablet for everyone.
When I decided on the NEC, I made a table of my top 3 or 4 most important factors (battery life, screen, weight, etc). Rank and weigh the factors based on how important they are to you, then score the tablets you are interested in.
Some help for your table:
The NEC has a great screen, it looks great outdoors compared to most LCD displays I've used, but is not an outdoor display and does look "washout" and dim in very bright sunlight. And, as you stated it is a pure slate so the keyboard is via USB only. Additionally, in my experience the battery life is only about 2.5 hours with wireless turned on.