In our 30+ years of tandeming, we have run the gamut of tire brands and sizes.
Diffferent batches of the same tire brands don't always behave the same +
road/riding conditions can vary greatly.
Currently we favor Maxxis Detonators (no, have NOT exploded one!) and Michelin Pros.
For stoker comfort, it may be nice to run one-size wider tire for her than on the front, as stoker absorbs most of the road shock/vibrations.
Experiment around a bit, and by the time you find your 'best ever' tire, they'll discontinue making it!