The first question I'd like to ask is, "How do you know you need at least 800W?" Have you gone to
http://www.extreme.outervision.com/psucalculatorlite.jsp ? I'm not saying you don't, or you haven't, but a lot of people overestimate their needs, based in part on low-quality units being unable to provide what is on their labels; so they just believe they need a bigger one. Please describe the rig you intend to power with this PSU.
Dirtyferret, I think you were a little harsh. Like you, I have seen many OCZ PSUs do well in competent technical reviews, but I have also read on forums where they didn't hold up. That's an impossible thing to quantify in a review, but it doesn't make reluctance to trust OCZ the sign of an idiot fanboy. Assuming this PC will be used in a high-stress environment, I'd much prefer to trust Seasonic or Delta over a relatively unknown OEM. Great Wall might be just fine, but they don't yet have the history to show it. OCZ might be a good bet, but for those who prefer not to bet at all, Seasonic is the safer choice.
Edit: Oh, and avoid Crappermaster. Although some of their really high-end units are decent, most of their lesser ones are not, and may possess liar-labels or claim protections that are missing (fact, not opinions; reviews at HardwareSecrets). That's dishonest, and a dishonest company does not deserve business for any of its products.