Personally I can't live without SCUMMVM, it works really well on the DS with stylus controls.
I don't like jenesisds, because it runs in native genesis resolution, and doesn't shrink it to DS resolution size. Which means certain percentage of the screen is cut off horizontally. Also it doesn't support 6button pads (or rather, it supports them very poorly), so you cannot play Lost Vikings and such.
SnemulDS can crash your micro SD. I'd stay well away.