It's a good thing that Slotkets (unlike procs) are cheap to buy (~$10-$20 US).  One can play the buy and try out deal with the major brands.
Steer clear well away from no-name brands.  That's just personal preference.  I at least know what I'm getting if I buy an Abit, Asus, MSI, or IWill Slotket.
Certain mobo manufacturer's recommend the same brand Slotket, but in my experience one can interchange any of these brands with no problems.  I haven't had any experience w/MSI (they are not locally available), but I've dealt with Abit's Slotket !!! and Asus' S370-133 and have had no problems with them.  Generally, this generation of Slotkets have the requisite voltage jumpers, FSB selection, and the option to enable SMP for dual Slot 1s.
If you've received generally-good feedback re: MSI's Slotket and if it's available from where you do business with, I'd say go for it.