TN panels
Most 17in panels are TN (Twisted Nematic) technology.
These are popular due to their low cost.
TN panels have relatively poor viewing angles although they have been recently improved upon using 'TN+film' technology, where a layer of special film is added.
Vertical viewing angles are especially bad. Looking at even a modern TN panel from above or below can result in colour shifts.
Most TN panels use 18-bit colour and deliver less accurate colours making them not ideal for applications such as photo editing.

MVA panels (PVA)
MVA or Multi-domain Vertical Alignment panels can achieve much deeper blacks (and hence better contrast ratios) than TN panels. They have wider viewing angles and superior 24-bit colour rendering with up to 16.7million colours. However, their cost is higher.

IPS panels
The most expensive panels are currently based on IPS (In-plane switching) technology.
They can achieve very wide viewing angles and excellent colour rendition. More recent S-IPS (Super IPS) panels achieve similar quality but at a much reduced cost.
For critical colour-based work, S-IPS panels offer the best quality but they are not without disadvantages. Their internal design means slightly less of the viewable area is given over to actually producing light, sometimes resulting in reduced brightness. Black levels can also suffer a little when viewed at wider angles.