i found sociology really interesting (some of it is a bit dry but mostly i really enjoyed it) and it goes really well with psychology - some of the content for research methods is all the same, which i found really helpful as i knew it really well!! both have a lot of case studies and names to remember, and i found i got some mixed up so watch out for this! but they do go really well together, and i loved sociology, obviously this depends on your topics so maybe look over the modules as you dont want to do something you dont enjoy as you wont do well in it