For the majority of applications, the CPU can be the most expensive and most important and most researched component of a desktop machine. In a handful of scenarios (perhaps where specific features are required, or for single GPU gaming) it comes second on the list of important components but it is still a big piece of the puzzle. The CPU can determine responsiveness, throughput, and feel, and no matter how good the rest of the system is around it, a bad CPU can bring a negative experience to a work flow. 

That being said, for a lot of everyday tasks, one might consider todays level of CPU compute power enough for the office environment. Web browsing, email, watching videos and basic photo editing tools are all well catered for. Buying a faster more expensive processor means when the workload hits peak usage, the system can process quicker and responsiveness is still present. No-one wants to tell the boss that the work is not complete because the system is running slow, or that the family cant watch a particular Blu-ray that evening because it isnt encoded for the home NAS.

Therefore when it comes to a holiday guide for purchasing CPUs, we have to split into several separate use cases, which might also have their own niche subcategories. A number of these use cases are particularly obvious, so we will address these first. This year at AnandTech we have specifically reviewed 24 different CPUs and tested many more, and the benchmark details can all be found in our comparison results database Bench.