There are some factors when you choose a right graphics tablet to benefit your needs. In my opinion the size is first factors to consider. The size, I mean, not the actual size of the tablet, but the active area. Accurately, the active area is the pressure sensitive surface receives the signal from the stylus pen, so that the active area is smaller than the tablet.
For example, Wacom Intuos Small Tablet:
Product size: 8.2 by 6.9 inches
Active area: 6 by 3.7 in
If dimensions are only told in advertisement, Minus anywhere from 2-5 inches of width and length and then get active areas
A lager or small graphic pad or tablet may trouble you a lot because of the motion of arms or the size of the fingers. So the size of the tablet should actually in proportion to your fingers and arms. By the way, a lager surface may be more desirable, but the price will definitely be higher.
For example, Wacom Intuos Pro Pen and Touch Large Tablet (PTH851)
On the other hand, the lager the dimensions of product is, the more desktop will be taken.
According to 4:3 aspect ratio of traditional computer monitors, the 4×5, 6×8, and 9×12 sizes are popular. However more sizes have been developed by manufacturers to meet the new needs for widescreen monitors. most of them are from Wacom. In my opinion, the 6×8 is the best choice.
Recently, a new tablet have been produced, the Interactive Pen Display, by Wacom. Your natural creative works will be directly seen on screen of the tablet. How excited! As it is a new product, the price is high (over $ 900 or more). If you are hobbyists and your budget is available, it will bring you lots of fun. But, personally, professional artist have better consider it seriously before buying it. Because sensitivity pressure bug have been mentioned in some reviews. Get more reviews about Wacom Cintiq 13HD Interactive Pen Display