I still think the rover's set of instruments are more useful then Beagle 2's instruments because of mobility. It gives them abilities closer to that of humans.

The Mossbauer Spectrometer on Opportunity would of produced almost no useful science if Opportunity didn't have the ability to drive forward 30 feet to get to the outcrop.

I think even if Beagle 2 had survived, it wouldn't have produced as much science as the rovers are. The only exception is the very slim chance its GAP could of detected life. Unless Beagle landed in the perfect location, many of its instruments would of been almost useless.