I think a useful combination of resources for universal algebra would ideally, when taken together:
- Provide ample motivation behind the various developments in the field.
- Either provide powerful intuitions, or avoid them altogether, in an effort to not cripple the learner's imagination.
- Provide a clear formal development (or, minimizes the number of "rabbits pulled out of a hat").
- Be self-contained.
- Be well written.
I look forward to your suggestions, and thank you sincerely in advance!