The antonyms for the term "more ill-conceived" are well-planned, thoughtful, and wise. The phrase "ill-conceived" refers to an idea or plan that is poorly thought out or lacking in logic, and "more ill-conceived" would indicate an idea or plan that is even worse than one that is simply "ill-conceived." Therefore, the opposite of this would be a plan that is carefully considered, has been thought out in detail, and is based on sound reasoning. Synonyms for "well-planned" could include terms such as thorough, methodical, and meticulous. In contrast, antonyms for "ill-conceived" fundamentally represent characteristics, ideas, or actions that are appropriate, well-grounded, and well-thought-out.