I look forwards to seeing what answers you get

plastic sides are the best for most of our home machines. Cardboard will leave dust down in the bobbin area. I believe the sideless ones are for multi needle machines. My preferred brands are Nebs and Fil-Tec. I have used some from Amazon (I can't remember the brand) and did not like them. Hugs. Nan

I use both cardboard sides and plastic ones... I have never had issues with either of them. I have tried the highly popular magnetic core bobbins, but don't think they work any better and they are quite expensive compared to the ones I use...I do not get the hype around them. I have used the bobbins from Metro Embroidery and they work very well and are a good price. I also use their Metro Pro embroidery threads and stabilizers and have for over 13 years with no issues. I have never paid more than $25 for 144 pre-wound bobbins. I use the plastic ones in both my Valiant (Size L) and Ellisimo (Size A15) and the cardboard sided for my Valiant.

mrskiki and dragonflyer have given you excellent advice. I've used the Neb (plastic sided) bobbins in my embroidery/sewing machine since I bought my first machine with no issues. The cardboard sided bobbins are used in my multi needle machine. I purchase most of my embroidery supplies from Allstitch and again, I have never had an issue with this company I truly think that it is important to use good quality products and companies. I hope this helps.

I was told by my HV dealer that non-HV bobbins would not work in my machine (which uses a bobbin with a flat bottom and convex top). Research suggested otherwise. I contacted several vendors stating my concerns. Two vendors graciously provided me with a single "sample" bobbin. No problems encountered with the "samples." I have been using prewound bobbins ever since.