I've found error theory, emotivism, etc. quite compelling, but I noticed that most philosophers are moral realists, though PhilPapers doesn't ask specifically about moral objectivism. As a non-philosopher, I feel that there may be considerations that I haven't come across. The SEP entry seems a bit lacking to me considering it's just a supplement to the entry on moral anti-realism, and there doesn't seem to be an IEP entry specifically focused on moral objectivism, just a tiny section in the entry on moral realism.