The lower end ones will give you the most for your money. It's gonna depend on where you buy it but the 2800 or 3000 will be a good value. You can graph them and see which one has the steepest slope. The one at the end of the steepest slope will generally be the best buy.
I completely disagree with the previous two responders. They seem to be thinking about price only. Just because something's cheap and fast doesn't mean there's not a faster, more expensive model that's a better value. If things were so cut and dry as TheRod says then why would we have benchmarks? The cheapest CPU might be nice, but not if it'll be useless for gaming overnight.
I suggest you not go with anyone's opinion and use what Tom's Hardware (and other sites) have given you. Go look at the latest CPU reviews and see how all of the latest models worth anything stack up to each other in the applications you plan on using them in. Then go get prices for the CPUs that are the most attractive to you and compare and contrast increases in speed to increases in $$.
2 years ago I got a P4 platform with a 2.4B because it was used and cheap. At the time, the fastest CPU was the 3.06B. Did anyone need a 3.06B for gaming back then? No. Would a 2.4B still be good for gaming? Yes.
The best deals for PERFORMANCE users are often in the MIDDLE of the pack. The 2.8C and A64 3000+ are great for games and will remain so for a while to come. For overclockers these become an even better deal, but even without that they have a better price/performance ratio than faster processors of the same core type.
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