I have a Wacom tablet. Wacom is considered industry standard. However, IMHO tablets are not really suitable for video editing or compositing (After Effects). If anything they will slow you down. They are perfect for image manipulation (Photoshop) and painting.
My advice would be to invest in a good quality keyboard and possibly a jogger wheel. I use a Contour Shuttle 2.
Contour Design ShuttlePRO V.2 - Black: Amazon.co.uk: Electronics