Concerning Intel processors, they are aimed at the high end market. The lower end models are not able to compete with AMD’s prices and/or speed. But for the overclockers and high end market, they are the most appropriate in my opinion. For that reason I won’t recommend Intel processors for Basic systems since the Celerons that are aimed there are not even fighting a losing war with their AMD counterparts, they already lost.
For a budget and overclocker system, the Pentium 4 2.4c processor is the best choice. It is fast enough on its own and will usually overclock well easily.
For a high end system, a Pentium 4 3.0c is the choice. Very fast and reliable, nothing too special to say about it. The Pentium 4 3.2c is out but it is still too expensive and simply not worth the money.
For the high end overclockers, the Pentium 4 2.8c is the best choice. Those will be able to be overclocked far enough and when paired with the proper cooling and very good memory modules, the memory can follow them at 1:1 operation where the lower models will have to use FSB dividers since almost no memory can reach as high as they will go if overclocked to the limit.
For workstation/office PC’s, the Pentium 4 2.6c is the choice. They offer the best value for money and the Hyperthreading will help with most common applications. Again, depending on the load of work a faster CPU is better most of the time. However, for the most common tasks, 2.6c will suffice.