AMA melodies of the Danube or Blue Danube Discovery

we are trying to decide between these two cruises. One ends in Vilshofen before going to Prague and one ends in Nuremberg before going to Prague. Just curious if one is more desirable than the other. Also I think September sounds good, but prices are lower at the end of October. Also Bratislova is bypassed if you go later in The fall. Is it much colder in late Octobermor early November? Thanks for any input you can provide.