Wacom's line of creative pen tablets are top of the line. You can't really go wrong with anything from the Intuos line but there are some pretty good competing drawing tablets availible.
If you want the best digital drawing tablets with a built in screen on the market the Cintiq line is for you. The quality and reliability comes at a price and there are several new tablets on the market that are quickly catching up wi the Cintiq's quality for a fraction of the price.
The next generation of built in screen drawing tablets are fully featured computers. Wacom has two models, the Companion that runs full Windows 8 and the Hybrid which is a high end Android tablet that's great for drawing.
Cintiq Companion $2100.00
Cintiq Hybrid $999.00