What's the difference between black currants and red currants?
Blackcurrants and redcurrants are simply subspecies of the same berry-producing shrub.  Besides their color, they differ only slightly in flavor; red are somewhat more tart than black.  For most purposes, such as in jams or baking, they're basically interchangeable.  When dried they're also easily substituted for raisins or sultanas.

There's really no basis for recommending one over the other beyond personal preference.  For your cereal, museli, granola, whatever, try both and see what you like.