We’ve been using Exercises in English workbooks, but they are pretty confusing - I’ve started using the Spectrum Language Arts series very recently - but so far I like what I see! I purchased the workbooks on Amazon, and bonus - the answers are included - so you don’t need to get a teacher’s manual! They have sample pages to look at on Amazon as well - so it might help you see if it is your style - if you like it or not.
The workbooks seem simple, but I think it is just because they actually do a good job making grammar seem simple and explain it and present it in a way that makes it more simple. The worksheets are still bright and colorful for older grades. They seem to move at a proper pace - not too much information at once, but not so little that your child would get bored. 