IT is down to your budget and requirement.
ROG series has been traditionally aimed at higher segment. The previous iterations of ROG had significant advantages over non ROG boards when it comes to overclocking stability. I am not so sure about P67 offerings at this stage.
I would skip P67 at this point in time if budget is not an issue. Z68 has all the advantages of P67 + H67 combined and none of their disadvantages. If you are considering these boards that you have mentioned, you have enough budget to skip P67.
I personally have P8Z68 Deluxe and its rock stable. Easy to overclock with K series CPUs.
P8Z68-V Pro is cousin of deluxe version. You can buy deluxe if you dont need the on board display connectors and prefer the other extras like other I/O ports on backplate and dual LAN.
Otherwise both are almost identical in terms of performance and stability. Deluxe has little more features, little better cooling than V-Pro.
Unless you want mATX board, skip Gene-Z. Too much cost premium for what it offers.
Maximus IV Extreme-Z (not to be confused with Maximus IV Extreme) on the other hand is whole different story, its expensive but does give you that little bit extra with NF200 chip and better power delivery components + more USB 3 ports on backplate. If you want absolute best, get Maximus IV Extreme-Z. You will have to fork out some serious $$$ for that.
Otherwise get P8Z68-V pro or P8Z68 Deluxe.
None of these boards will have any issues running SB chip close to 4.5-5Ghz range 24x7.
If you are really into extreme overclocking or competitive overclocking or interested in looks got for Maximus IV Extreme-Z.
mrcool63 said:
maximus IV extreme... the gene-z is the smaller version of the IV extreme. The p67 chipset is more suited for max oc'ing than the z68.
That is not true at all. Z68 does not restrict you in any way when it comes to overclocking. Its as good if not better as P67 when it comes to overclocking. Dont let the presence of virtu fool you into thinking this is like H67 and only for those who want to use integrated display of SB cpus.