There is no denying that supercard dstwo is the best one. In fact,there have many slot-1 cards are good too,please check this comparison list for each flashcarts :
http://wiki.gbatemp.net/wiki/Flashcart_Comparison_Chart
I didn't know they made an MSU cart for the Genesis.... I knew about the SNES one and the library for that is rather large but the Genesis one has very few games