plots = RegionPlot3D[#, {Q1, 0, 1/2}, {Q2, 0, 1/3}, {Q3, 0, 1/4}] & /@
{j1, j0 && MUB, j0 && Choi};
coords = Cases[#, GraphicsComplex[x_,__] :> Median/@Transpose[x], All][[1]]& /@ plots;
labels = {"PPT", "MUB", "CHOI"};
texts3d = Graphics3D[MapThread[Text, {labels, coords}], Axes -> True];
Show[plots, texts3d, AxesLabel -> (Subscript[Q, #] & /@ {1, 2, 3})]
