I have a 1/4" foot for my Janome, but I was still having issues with it. I read somewhere that most of them are not really a true 1/4", despite the effort. I started using Bonnie Hunter's seam guide, and have been getting a more accurate 1/4".
I found the difference in end product when I was piecing the mystery BOM I am doing from my LQS. I started with my 1/4" foot and the finished strip sections ended up 1/8" too narrow, so I had to rip them out and resew them. I decided to try the seam guide (you then mark the edge - she suggests a hard edge like a cut up card. I use a Starbucks card) and they were spot on. I still have to watch, but it comes out better than using my 1/4" foot.