It's possible that none of them are very accurate, if your resolution is low in relation to feature size. What's your pixel spacing, and how many pixels are representing this particle?
The ellipsoid's volume is only an accurate reflection of the fitted shape's volume if the fitted shape is at least approximately ellipsoidal. If it's something else, the ellipsoid dimensions are likely to be way off. You can check this out by cropping down and isolating this particle, then looking at it with the 3D visualisation.
The enclosed volume is measured from the surface mesh. If the particle is close in size to pixel spacing and you have applied a bit of smoothing or subsampling during mesh creation, it's likely that your enclosed volume is completely wrong. Vol. is just a count of pixels in the particle multiplied by the x, y & z pixel spacing, so is probably the least inaccurate / best estimate in this case.