I suspect the OCZ is the best of the three (as it is the most expensive), but between the ZALMAN and the SHARKOON (both at about the same price) which is the best?
Chieftec don't make PSUs. Their PSUs are made by CWT, Sirtec and Delta. Some of the models aren't bad. Some are similar or even identical to those sold by Corsair. So Corsair should avoided like plague as well... Can't comment on MS-Tech. Going by their cases, seems to be another generic brand/distributor that sells rebadged-only products. But hell knows what's inside their PSUs. Sharkoon model seems pretty good http://www.computerbase.de/artikel/netzteile/2013/sharkoon-wpm500-im-test
Without being an expert I think the inside of the SHARKOON looks quite messy in some of the photos in the above link.
That's a good thing. Better PSUs tend to be more populated than cheap ones. Review says it's based on CWT's DSAII platform, also used in PSUs like Corsair CX. Should be pretty good budget unit.
Well, at least it is built by CWT but it has C(r)apxon caps. Avoid that one like a plague. 85c rated primary cap from Capxon... That's baaaad.
My Chieftec is made by Channel Well and so far it preforms excellent, its 90Gold @400w and it was quite cheap ~ 100€.. http://www.xbitlabs.com/articles/cases/display/psu-520w-650w_7.html#sect0 lol I needed a quick replacement 3-4moths ago, my old died after 5years - 2nd lightning strike, it survived one 4 years earlier xD