Just to clarify what amuffin is saying is; if you plan to overclock ivybridge might not be the best choice because voltage increases on ivybridge CPUs increase core temperature much more than they do with sandybridge chips.
If you never plan to overclock then ivybridge is the better choice. You also have to consider things like PCI-E 3.0 which are ivybridge only.
As stated by noise, Overclocking will be limited (to about 4.1Ghz max with a tower cooler like evo 212). And if you'll be getting a PCIE 3.0 motherboard and graphics card, then theres nothing that should stop you from getting an Ivy Bridge CPU.
You can also use Virtu MVP which uses your iGPU (HD4000 for the IB) and pairs it with your dedicated Graphics Card. Virtu MVP is only available for IB! So be careful.
If you dont need Virtu MVP.. or dont have a Z77 motherboard or a Z68 motherboard with PCIE 3.0..
Then.. Sandy Bridge is much better!
- Im currently rocking a 3570K with a CM 212 EVO and a Z77X-D3H Motherboard.
Interesting article. Certainly suggests there is only a small amount to be gained in gaming benchmarks with 3.0. Will be interesting to see the same results in the next GPU series' (and next GPU melting game) and whether that 1% increases to a more serious figure.