Definitely check out the LIfe of Fred series if you want quirky and fun.

The Key to Algebra workbooks are self-explanatory and introduce most of the topics of Algebra 1 at a very basic level. Not so much fun, but my dd enjoyed them.

AOPS is way challenging. I think you can pop on Alcumus (their online database of questions) and check out for yourself if your child would find them fun or not. DD11 is doing AOPS now, but is glad she had some foundational algebra before she started.