OP, to answer your question, Genesis Black Magic is a good all round black polyester. If you like feel and provide spin on your own, then it's a good choice. WeissCANNON BlackFiveEdge is a solid baseliner string. It has lower power and is stiffer than Black Magic, but it provides fantastic spin and has excellent tension maintenance. Discho Iontec also gets great reviews for an all round polyester, although according to some, the earthworm color plays better than the black.
Personally, I would avoid using RPM Blast or Black Code as they are overpriced given their relatively short life span.
All aboard the Gulbis bandwagon!