ceramic balls that work best for pressure loaded bearings are made of Si_3Ni_4. If you want to have the best possible quality you can get balls with better tolerances. Most balls you can buy from rc companies are grade 3 or 5 but I know some 12scale guys using grade 25. Havent seent anything better than 25 but you will be fine with any grade 3 or 5 balls.
If you want the best balls possible the limit should be grade 1000 afaik. No idea how much they cost but pretty sure its nonsence for rc
to answer your question:
I wouldnt spend much time thinking about it, both will do the job. I had some Team C ones, tehy should be the same as Ansmann and they are great too. Get those you can get cheapest and fastest. You can use them in most cases at least one year nonstop racing.