If you don't have any agression issues all of them could work with enough water changes. However, a JD can breed with either a convict or firemouth, and a convict can breed with a firemouth. So be careful about getting the right sex cichlid.
A GT won't mate with a convict or firemouth.
If you want to keep to 1 water change of 75% per week as full grown adults, I would only stock it as the following:
1 GT, 1 FM, 1 Con
or
1 JD, 1 FM, 1 Con
or
2 FM, 2 Con