Other than Simply Homeschool integrated maths cores the maths options are split into Textbook, Online and other things.

Textbook options include:

SAP Learning Maths: For Grades 1-6 and these can be found in Just Good Books. This series is a Singapore Maths series. It is very clear and also economical. The levels are quite challenging and, in general, we suggest you will need the grade below your child's normal year. SAP Learning Maths books are available from Five Senses Education.
ICE-EM Cambridge: For grades 5-10 and is available with a discount through Five Senses Education. ICE-em works well for students who enjoy traditional maths textbooks and/or work well with school-style maths. The explanations for each concept are visual and clear, which makes it useful for parents to assist their children in learning maths. We recommend completing the most difficult questions in the review at the end of each chapter before starting the chapter, to assess the student's level of skill and understanding. You do not need to complete every activity in the text.

Online Options include:

Maths Online: Includes access to all grades and is available with a 50% Discount through our Resource Shop. This is the online program that we recommend – with the 50% discount it works out to approx $150 per year. You can do a free trial and choose your payment frequency.
Khan Academy: This is a free program but can be distracting, as there are many other subjects and videos on the site. If you are going with this option, we suggest you supervise your child to ensure they don’t end up somewhere else in the site away from their actual “lesson”.

Other options:

Life of Fred: Covers grades 2-7 and is available in Just Good Books. Life of Fred works well for some students who are resistant to other styles of maths. The books are quite expensive but are non-consumable and can be resold when you are done with them. Life of Fred is written as a story, integrating maths, and involves very few questions. Questions are often complex and involve thought and problem-solving.
There are also several 'Living Maths' books in Core Programs and Just Good Books such as A Year on Our Farm, Think of a Number and the Phantom Tollbooth. Living Books are used in Charlotte Mason style education. These books integrate story and maths.