Generally the pixelation you refer to, is due to bad media (or bad burns). Some of the media you listed is known to be problematic. You should not be burning your media at 16x, unless it is verbatim or taiyo yuden, and even then, it is a good practice to burn at slightly under the media’s rated speed. You should burn at 12x or 8x, depending on the brand of media. Stick on labels are known to be a problem. I do not recommend using stick on labels… EVER!
See if you can find some good verbatim, taiyo yuden, or other Made In Japan media, and try doing another one and burn at 8x or 12x and see if that resolves the problem. While there are other things that you could try, this is the cheapest, fastest and most likely fix for the problem.