There are a few things to consider when answering this question. The first is that 1 liter (L) is equal to 1,000 milliliters (mL). So, if you were ask which is more, 1 L or 1 mL, the answer would be 1 L. However, if you were asking which is more, 1 mL or 0.001 L, the answer would be 0.001 L (or 1 mL).
It's also important to note that the metric system uses the International System of Units (SI), and in SI, the official unit for volume is the cubic meter (m^3). So really, the answer to this question should be: it depends on what you're measuring! If you're measuring something very small, like a drop of water or a grain of salt, then milliliters will be more appropriate. But if you're measuring something larger, like a swimming pool or an oil drum, then liters will be better suited.
To recap:
-1 liter (L) equals 1,000 milliliters (mL)
-The metric system uses cubic meters as its official unit for volume
-It all depends on what you're measuring!