If you just want to read
Then eInk is better than LCD. But I found the regular kindle too small.
Most of the PDFs I want to read are SCANS of old books. The text is just too small.
If you are reading a book you can't be zooming and scrolling on each page either.
If I want Video the TV is best, or if on a plane/train the old Archos 4.3" with 800x600 and 160Gbyte HDD.
If I want to do a mix of things a real laptop running Windows XP is still best. 1600 x 1200. I have separate Ubuntu laptop.
The tablets seem best suited for browsing material and people with short attention span:
Reading 3 page docs rather than 300 pages
Watching 3 minute YouTube rather than 3 hr HD feature film
Writing 3 line message/Note rather than 3 page to 30 page document.
Flipping through a dozen web sites rather than maintaining one or reading in depth Articles.
So Smart Phones, Tablets. Real Notebook/Laptops, Pocket PMP too large as a phone too small as a tablet and eReaders are really complementary different markets.