Usually, the best overclockers are the lowest speed CPU. They do not necessarly reach the highest speed, but they usually have lot more "headroom".
For example : the AMD Barton 2500+ is often prefer to the 3200+, because it can be clocked in the same speed range for a fraction of the price. The same thing for Northwood Pentium 4 CPU, the best overclocker's are the 2.4GHz to 2.8GHz versions. They cost less and can reach appr. the same speed. It's why I would get a Celeron D 2.8GHz, it will reach nearly the same speed when overclocked, and it will cost less.
--
It's tricky to use words like <b><font color=green>AMD</font color=green></b> or <b><font color=blue>Intel</font color=blue></b> in a signature some users could think your are biased.