I am also the mother of a 4 year old daughter with long thick straight hair. I am not sure what type of hair your daughter has (i.e. straight, curly, wavy, etc), but hopefully I can help.
First let me say that I agree with you on the detangler sprays, as they just leave the hair greasy looking and feeling. And, because our daughter's have thick hair, the amount you would need to use is just not worth it.
Second, I realized that when brushing my daughter's hair with ANY toddler brush, the process seems to take forever, and her hair inevitably gets caught and pulled. Because their hair is long and thick (which is not too typical of toddlers), I do not think that the brushes are geared for them. Their hair is too adult like, and needs to be handled differently. One day I decided to use my own brush (just an adult sized Revlon cushioned bristle brush). I can not tell you how wonderful it works! Not only does the larger surface area make for faster overall brushing, but her hair does not catch on the bristles so there is no pulling. And, because there is no excess brushing, her hair looks so much healthier. (Sometimes after a long fight with a smaller brush, her hair was left frizzy).
I would suggest saving your money on any fancy toddler brush, and just start using an adult sized cushion brush. I usually brush her hair entirely before handing over the brush for her own use. Also, I brush before bed to make the morning brush more bearable for us both. Many times I will put it in a loose braid, which helps avoid knots too. I have also noticed that getting her hair trimmed has a lot of benefits: it makes her hair look and feel healthier, it makes her hair seem to grow faster, and it helps discourage knots/tangles.
Hope this helps!