We’ve used Singapore K, 1A/1B, and now in 2A. My daughter is finishing up 2nd grade right now and we’ll do 2B into the start of 3rd grade. You probably know already that the numbers designated on the books do not corrrespond to grades. 🙂
We used Singapore K with Miquon, Singapore 1A/1B with MFW First Grade, and then we tried Math Mammoth Grade 1 last summer to keep things fresh, which was drudgery compared to Singapore, then she started Math Lessons for a Living Education Book 2 at the start of 2nd grade. We got half way through the book and both realized that she needs Singapore. She’s just that Singapore math brain sort of girl.
We will finish up 2A and use the summer to review with MLFLE2, but then back to Singapore and only Singapore with 2B/3A come August and 3rd grade.
I cannot sing the praises of Singapore enough. It teaches mental math in amazing ways and there are not pages and pages of practice, ad nauseum, but that is again preference and may not work for all kids, obviously. 😉 My daughters think mathematically differently with Singapore (and Miquon) than they do after using other programs. The only thing that I do teach above Singapore is vertical addition/subtraction earlier, which just means creating a few practice problems on the art easel/chalkboard here and there.
It is also affordable and simply presented for me and I do appreciate that the workbook is in black and white versus color.
Good luck in your choices!