My most favourite: Q6600 G0. Performance out of this world for 2007, at a 'reasonable' $300.
- Very good overclocking for a quad (42% for me @ 3.4ghz)
- The CPU wasn't picky about needing an enthusiast board to overclock --> this was accomplished on a budget P35-DS3L ($90-100 board)
- Lasting performance: I bet even today, Q6600 @ 3.4ghz can keep up with the likes of Phenom II X4/X6/Bulldozer in a lot of tasks, including games. Not bad for a CPU pushing 5 years old.
- My first ever quad
If I was building computers earlier, I might have voted for the Celeron 300A.
E6400 @ 3.4ghz gets the "most improved" generational jump from me as I was coming from Pentium 4 C 2.4 @ 3.2ghz. However, I still feel Q6600 can be used by many people for another 1-2 years while E6400 is still only a dual core.
I agree, the Q6600 has lasted a very long time. It gets the job done, but I'm really looking forward to upgrading to Ivy Bridge. It'll probably be a nice upgrade for me.