I was asked this kind of curriculum question recently, and I thought I'd post it here too in case there are others who will get helped...
I am torn between using Right Start, Singapore, or Math Mammoth with my daughter who is just starting her schooling journey. Do you have any insight to share that might help?
Yes. If you are torn, try Singapore with Math Mammoth (if you can afford both). I've heard from people who use both and say they go well together, because Singapore is somewhat lacking in practice exercises.
There are lots of folks who use two curricula for math. You would basically use one of them as your "spine" that you go by, and then for each topic, check the corresponding lesson in the other, if it has good explanations or problems. You wouldn't do all problems in both.
Then, if you like RightStart, buy their math games book (but not the whole curriculum), which allows you to incorporate their games into your math lessons here and there.