One angel?
Some other things to think about:
You really need the number of cory cats to be higher. At least 3 of the same type.
Your pristella's would probably prefer to be at least 5.
Not sure why you're having trouble with Bolivians, who tend to be hardier than blue rams. I know what you mean about the apistos being a bit small. What about a pair of curviceps? (laetacara curvicep, I think.) A dwarf cichlid about the size of the Bolivians. (I'd probably re-home the Bolivian in that instance.)
Some other things to think about:
You really need the number of cory cats to be higher. At least 3 of the same type.
Your pristella's would probably prefer to be at least 5.
Not sure why you're having trouble with Bolivians, who tend to be hardier than blue rams. I know what you mean about the apistos being a bit small. What about a pair of curviceps? (laetacara curvicep, I think.) A dwarf cichlid about the size of the Bolivians. (I'd probably re-home the Bolivian in that instance.)