In general-purpose DC power link decoupling, capacitance is usually irrelevant as long as you have enough, and typical suggested values already have ample capacitance margins. For example, a digital CMOS IC where 100nF is recommended per power pin may actually work exactly the same with anything in excess of 5-10nF. So if one 100nF MLCC is 30nF at the DC bias and another is 60nF, it doesn't matter. (Regarding regulator IC output caps, the requirements for loop stability are more important, and recommended capacitance value should be respected. If they recommend a "2.2uF MLCC", then they assume it has some amount of DC bias effect, likely that actual 1uF is enough, but you can still get in troubles if you pick the absolute worst offender 2.2uF part.)
What actually matters is parasitic inductance, and I have good news for you: because all MLCCs use the same physical construction pattern, the ESL is only dependent on the footprint size and your layout (how many vias, and how close, you use to get to the ground plane, etc.), so a 0402 is better than 1206, but the manufacturer does not matter.
In large sizes (1206 and up), reliability things like soft terminations start to matter.
Both Samsung and Yageo are known brands. Just buy whichever is available at the best price.
What's your intended application for the 330nF parts? I.e., by "general decoupling", do you mean these go in the Vdd pins of some bog standard CMOS chips like microcontrollers, logic gates, maybe opamps? If this is the case, the best way to really optimize the design is to go to a smaller package instead of comparing manufacturers. Though, don't get me wrong, 0805 is perfectly fine.